Infusion pump assembly

ABSTRACT

A wearable infusion pump assembly including a reservoir for receiving an infusible fluid, and a fluid delivery system configured to deliver the infusible fluid from the reservoir to an external infusion set. The fluid delivery system includes a volume sensor assembly configured to receive a quantity of the infusible fluid from the reservoir. The volume sensor assembly includes an acoustically contiguous region having a volume that varies based upon the quantity of infusible fluid received from the reservoir, and an acoustic energy emitter configured to provide acoustic energy at a plurality of frequencies to excite a gas included within the acoustically contiguous region.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of the following provisional patentapplications, each of which is herein incorporated by reference in theirentirety: U.S. Ser. No. 61/018,054, filed Dec. 31, 2007; U.S. Ser. No.61/018,042, filed Dec. 31, 2007; U.S. Ser. No. 61/017,989, filed Dec.31, 2007; U.S. Ser. No. 61/018,002, filed Dec. 31, 2007; U.S. Ser. No.61/018,339, filed Dec. 31, 2007; U.S. Ser. No. 61/023,645, filed Jan.25, 2008; U.S. Ser. No. 61/101,053, filed Sep. 29, 2008; U.S. Ser. No.61/101,077, filed Sep. 29, 2008; U.S. Ser. No. 61/101,105, filed Sep.29, 2008; and U.S. Ser. No. 61/101,115, filed Sep. 29, 2008.

FIELD OF THE INVENTION

This application relates generally to fluid delivery systems, and moreparticularly to infusion pump assemblies.

BACKGROUND

Many potentially valuable medicines or compounds, including biologicals,are not orally active due to poor absorption, hepatic metabolism orother pharmacokinetic factors. Additionally, some therapeutic compounds,although they can be orally absorbed, are sometimes required to beadministered so often it is difficult for a patient to maintain thedesired schedule. In these cases, parenteral delivery is often employedor could be employed.

Effective parenteral routes of drug delivery, as well as other fluidsand compounds, such as subcutaneous injection, intramuscular injection,and intravenous (IV) administration include puncture of the skin with aneedle or stylet. Insulin is an example of a therapeutic fluid that isself-injected by millions of diabetic patients. Users of parenterallydelivered drugs may benefit from a wearable device that wouldautomatically deliver needed drugs/compounds over a period of time.

To this end, there have been efforts to design portable and wearabledevices for the controlled release of therapeutics. Such devices areknown to have a reservoir such as a cartridge, syringe, or bag, and tobe electronically controlled. These devices suffer from a number ofdrawbacks including the malfunction rate. Reducing the size, weight andcost of these devices is also an ongoing challenge. Additionally, thesedevices often apply to the skin and pose the challenge of frequentre-location for application.

SUMMARY OF THE INVENTION

According to a first implementation, a wearable infusion pump assemblyincludes a reservoir for receiving an infusible fluid, and a fluiddelivery system configured to deliver the infusible fluid from thereservoir to an external infusion set. The fluid delivery systemincludes a volume sensor assembly configured to receive a quantity ofthe infusible fluid from the reservoir. The volume sensor assemblyincludes an acoustically contiguous region having a volume that variesbased upon the quantity of infusible fluid received from the reservoir.The volume sensor assembly further includes an acoustic energy emitterconfigured to provide acoustic energy at a plurality of frequencies toexcite a gas included within the acoustically contiguous region.

One or more of the following features may be includes. The volume sensorassembly may further include a first acoustic energy receptor forreceiving at least a portion of the acoustic energy provided by theacoustic energy emitter, and for defining an acoustic response for eachof the plurality of frequencies. A second acoustic energy receptor mayreceive at least a portion of the acoustic energy provided by theacoustic energy emitter and for defining an acoustic reference for eachof the plurality of frequencies.

The acoustically contiguous region may include a variable volumechamber, that may have a volume that varies based upon the quantity ofinfusible fluid received from the reservoir. The acoustically contiguousregion may also include at least one fixed volume chamber, which mayhave a volume that is constant regardless of the quantity of infusiblefluid received from the reservoir. At least one acoustic port mayacoustically couple the variable volume chamber to the at least onefixed volume chamber.

The first acoustic energy receptor may be an invariable microphonepositioned proximate the variable volume chamber. The second acousticenergy receptor may be a reference microphone positioned proximate theat least one fixed volume chamber.

The wearable infusion pump assembly may further include at least oneprocessor, and a computer readable medium coupled to the at least oneprocessor. The computer readable medium may include a plurality ofinstructions stored on it. When executed by the at least one processor,the instructions may cause the at least one processor to performoperations including determining a phase relationship between theacoustic response and the reference for each of the plurality offrequencies. The computer readable medium may further includeinstructions for calculating a change of volume characteristic based, atleast in part, upon the phase relationship between the acoustic responseand the acoustic reference for each of the plurality of frequencies.

The wearable infusion pump assembly may further include a disposablehousing assembly, which may include the reservoir and a first portion ofthe fluid delivery system. The wearable infusion pump assembly may alsoinclude a reusable housing assembly, which may include a second portionof the fluid delivery system. A first portion of a pump assembly may bepositioned within the disposable housing assembly. A second portion ofthe pump assembly may be positioned within the reusable housingassembly. The pump assembly may be configured to extract the quantity ofthe infusible fluid from the reservoir and provide the quantity of theinfusible fluid to the volume sensor assembly.

A first portion of a first valve assembly may be positioned within thedisposable housing assembly. A second portion of the first valveassembly may be positioned within the reusable housing assembly. Thefirst valve assembly may be configured to selectively isolate the pumpassembly from the reservoir. A first portion of a second valve assemblymay be positioned within the disposable housing assembly. A secondportion of the second valve assembly may be positioned within thereusable housing assembly. The second valve assembly may be configuredto selectively isolate the volume sensor assembly from the externalinfusion set.

According to another implementation, a wearable infusion pump assemblyincludes a reservoir for receiving an infusible fluid, and a fluiddelivery system configured to deliver the infusible fluid from thereservoir to an external infusion set. The fluid delivery systemincludes a volume sensor assembly configured to receive a quantity ofthe infusible fluid from the reservoir. The wearable infusion pumpassembly also includes at least one processor, and a computer readablemedium coupled to the at least one processor. The computer readablemedium includes a plurality of instructions stored on it. When executedby the at least one processor, the instructions cause the at least oneprocessor to perform operations including calculating a first volumecharacteristic prior to providing the quantity of the infusible fluid tothe external infusion set. The computer readable medium also includesinstructions for calculating a second volume characteristic subsequentto providing the quantity of the infusible fluid to the externalinfusion set. The computer readable medium further includes instructionsfor determining whether an occlusion condition is occurring.

One or more of the following features may be included. The instructionsfor determining whether an occlusion condition is occurring may includeinstructions for calculating a differential volume from the first volumecharacteristic and the second volume characteristic. The instructionsfor determining whether an occlusion condition is occurring may alsoinclude instructions for analyzing the differential volume to determinewhether an occlusion condition is occurring.

According to another implementation, a wearable infusion pump assemblyincludes a reservoir for receiving an infusible fluid, and a fluiddelivery system configured to deliver the infusible fluid from thereservoir to an external infusion set. The fluid delivery systemincludes a volume sensor assembly configured to receive a quantity ofthe infusible fluid from the reservoir. The fluid delivery systemfurther includes at least one processor, and a computer readable mediumcoupled to the at least one processor. The computer readable mediumincludes a plurality of instructions stored thereon. When executed bythe at least one processor, the instructions cause the at least oneprocessor to perform operations including determining a quantity of theinfusible fluid delivered to a user via the external infusion set. Thecomputer readable medium also includes instructions for comparing thequantity of the infusible fluid delivered to a delivery target quantityto determine a differential quantity. The computer readable mediumfurther includes instructions for adjusting a subsequently deliveredquantity of the infusible fluid to offset the differential quantity.

One or more of the following features may be included. The differentialquantity may represent an over delivery. The subsequently deliveredquantity of the infusible fluid may be decreased by the differentialquantity. The differential quantity may represent an under delivery. Thesubsequently delivered quantity of the infusible fluid may be increasedby the differential quantity.

According to yet another implementation, a wearable infusion pumpassembly includes a reusable housing assembly, and a disposable housingassembly including a reservoir for receiving an infusible fluid. Areleasable engagement assembly is configured to allow the reusablehousing assembly to releasably engage the disposable housing assembly.The wearable infusion assembly also includes at least one processor, anda computer readable medium coupled to the at least one processor. Thecomputer readable medium includes a plurality of instructions stored onit. When executed by the at least one processor, the instructions causethe at least one processor to perform operations including executing oneor more hierarchical state machines to effectuate the delivery of one ormore bolus infusion events.

According to yet another implementation, a wearable infusion pumpassembly includes a reusable housing assembly, and a disposable housingassembly including a reservoir for receiving an infusible fluid. Areleasable engagement assembly is configured to allow the reusablehousing assembly to releasably engage the disposable housing assembly.The wearable infusion pump assembly also includes at least oneprocessor, and a computer readable medium coupled to the at least oneprocessor. The computer readable medium includes a plurality ofinstructions stored on it. When executed by the at least one processor,the instructions cause the at least one processor to perform operationsincluding executing one or more hierarchical state machines toeffectuate the delivery of one or more basal infusion events.

According to yet another implementation, a wearable infusion pumpassembly includes a reusable housing assembly, and a disposable housingassembly including a reservoir for receiving an infusible fluid. Areleasable engagement assembly is configured to allow the reusablehousing assembly to releasably engage the disposable housing assembly.The wearable infusion pump assembly further includes at least oneprocessor, and a computer readable medium coupled to the at least oneprocessor. The computer readable medium includes a plurality ofinstructions stored on it. When executed by the at least one processor,the instructions cause the at least one processor to perform operationsincluding executing one or more hierarchical state machines toeffectuate the execution of one or more occlusion detection events.

According to yet another implementation, a wearable infusion pumpassembly includes a reusable housing assembly, and a disposable housingassembly including a reservoir for receiving an infusible fluid. Areleasable engagement assembly is configured to allow the reusablehousing assembly to releasably engage the disposable housing assembly.The wearable infusion pump assembly further includes at least oneprocessor, and a computer readable medium coupled to the at least oneprocessor. The computer readable medium includes a plurality ofinstructions stored on it. When executed by the at least one processor,the instructions cause the at least one processor to perform operationsincluding executing one or more hierarchical state machines toeffectuate the execution of one or more pairing events.

According to yet another implementation, a wearable infusion pumpassembly includes a reusable housing assembly, and a disposable housingassembly including a reservoir for receiving an infusible fluid. Areleasable engagement assembly is configured to allow the reusablehousing assembly to releasably engage the disposable housing assembly.The wearable infusion pump assembly further includes a filling stationincluding an infusible fluid supply. The filling station is configuredto releasably fluidly couple the reservoir and effectuate the deliveryof the infusible fluid from the filling station to the reservoir.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features and advantages willbecome apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an infusion pump assembly;

FIG. 2 is a perspective view of the infusion pump assembly of FIG. 1;

FIG. 3 is an exploded view of various components of the infusion pumpassembly of FIG. 1;

FIG. 4 is a cross-sectional view of the disposable housing assembly ofthe infusion pump assembly of FIG. 1;

FIGS. 5A-5C are cross-sectional views of an embodiment of a septumaccess assembly;

FIGS. 6A-6B are cross-sectional views of another embodiment of a septumaccess assembly;

FIGS. 7A-7B are partial top views of another embodiment of a septumaccess assembly;

FIGS. 8A-8B are cross-sectional views of another embodiment of a septumaccess assembly;

FIG. 9 is a perspective view of the infusion pump assembly of FIG. 1showing an external infusion set;

FIGS. 10A-10E depict a plurality of hook-and-loop fastenerconfigurations;

FIG. 1A is an isometric view of a remote control assembly and analternative embodiment of the infusion pump assembly of FIG. 1;

FIGS. 11B-11R depicts various views of high level schematics and flowcharts of the infusion pump assembly of FIG. 1;

FIGS. 12A-12F is a plurality of display screens rendered by the remotecontrol assembly of FIG. 11A;

FIG. 13 is an isometric view of an alternative embodiment of theinfusion pump assembly of FIG. 1;

FIG. 14 is an isometric view of the infusion pump assembly of FIG. 13;

FIG. 15 is an isometric view of the infusion pump assembly of FIG. 13;

FIG. 16 is an isometric view of an alternative embodiment of theinfusion pump assembly of FIG. 1;

FIG. 17 is an plan view of the infusion pump assembly of FIG. 16;

FIG. 18 is a plan view of the infusion pump assembly of FIG. 16;

FIG. 19A is an exploded view of various components of the infusion pumpassembly of FIG. 16;

FIG. 19B is an isometric view of a portion of the infusion pump assemblyof FIG. 16;

FIG. 20 is a cross-sectional view of the disposable housing assembly ofthe infusion pump assembly of FIG. 16;

FIG. 21 is a diagrammatic view of a fluid path within the infusion pumpassembly of FIG. 16;

FIGS. 22A-22C are diagrammatic views of a fluid path within the infusionpump assembly of FIG. 16;

FIG. 23 is an exploded view of various components of the infusion pumpassembly of FIG. 16;

FIG. 24 is a cutaway isometric view of a pump assembly of the infusionpump assembly of FIG. 16;

FIGS. 25A-25D are other isometric views of the pump assembly of FIG. 24;

FIG. 26A-26B are isometric views of a measurement valve assembly of theinfusion pump assembly of FIG. 16;

FIG. 27A-27B are side views of the measurement valve assembly of FIGS.26A-26B;

FIGS. 28A-28D are views of a measurement valve assembly of the infusionpump assembly of FIG. 16;

FIG. 29 is an isometric view of an alternative embodiment of theinfusion pump assembly of FIG. 1;

FIG. 30 is an isometric view of an alternative embodiment of theinfusion pump assembly of FIG. 1;

FIG. 31 is another view of the alternative embodiment infusion pumpassembly of FIG. 9;

FIG. 32 is an exploded view of another embodiment of an infusion pumpassembly;

FIG. 33 is another exploded view of the infusion pump assembly of FIG.32;

FIGS. 34A-34B depict another embodiment of an infusion pump assembly;

FIGS. 35A-35C are a top view, side view, and bottom view of a reusablehousing assembly of the infusion pump assembly of FIG. 32;

FIG. 36 is an exploded view of the reusable housing assembly of FIGS.35A-35C;

FIG. 37 is an exploded view of the reusable housing assembly of FIGS.35A-35C;

FIG. 38A is an exploded view of the reusable housing assembly of FIGS.35A-35C;

FIG. 38B-38D are top, side and bottom views of one embodiment of a dustcover;

FIGS. 39A-39C are a top view, side view, and bottom view of anelectrical control assembly of the reusable housing assembly of FIGS.35A-35C;

FIGS. 40A-40C are a top view, side view, and bottom view of a base plateof the reusable housing assembly of FIGS. 35A-35C;

FIGS. 41A-41B are a perspective top view and a perspective bottom viewof the base plate of FIGS. 40A-40C;

FIGS. 42A-42C are a top view, side view, and bottom view of a base plateof the reusable housing assembly of FIGS. 35A-35C;

FIGS. 43A-43B depict a mechanical control assembly of the reusablehousing assembly of FIGS. 35A-35C;

FIGS. 44A-44C depict the mechanical control assembly of the reusablehousing assembly of FIGS. 35A-35C;

FIGS. 45A-45B depict the pump plunger and reservoir valve of themechanical control assembly of the reusable housing assembly of FIGS.35A-35C;

FIGS. 46A-46E depict various views of the plunger pump and reservoirvalve of the mechanical control assembly of the reusable housingassembly of FIGS. 35A-35C;

FIGS. 47A-47B depict the measurement valve of the mechanical controlassembly of the reusable housing assembly of FIGS. 35A-35C;

FIG. 48 is an exploded view of the disposable housing assembly of theinfusion pump assembly of FIG. 32;

FIG. 49A is a plan view of the disposable housing assembly of FIG. 48;

FIG. 49B is a sectional view of the disposable housing assembly of FIG.49A taken along line B-B;

FIG. 49C is a sectional view of the disposable housing assembly of FIG.49A taken along line C-C;

FIGS. 50A-50C depict the base portion of the disposable housing assemblyof FIG. 48;

FIGS. 51A-51C depict the fluid pathway cover of the disposable housingassembly of FIG. 48;

FIGS. 52A-52C depict the membrane assembly of the disposable housingassembly of FIG. 48;

FIGS. 53A-53C depict the top portion of the disposable housing assemblyof FIG. 48;

FIGS. 54A-54C depict the valve membrane insert of the disposable housingassembly of FIG. 48;

FIGS. 55A-55B depict the locking ring assembly of the infusion pumpassembly of FIG. 32;

FIGS. 56A-56C depict the locking ring assembly of the infusion pumpassembly of FIG. 32;

FIGS. 57-58 is an isometric view of an infusion pump assembly and a filladapter;

FIGS. 59-64 are various views of the fill adapter of FIG. 57;

FIG. 65 is an isometric view of another embodiment of a fill adapter;

FIGS. 66-67 depict an infusion pump assembly and another embodiment of afill adapter;

FIGS. 68-74 are various views of the fill adapter of FIG. 66;

FIGS. 75-80 depict various views of an embodiment of a battery charger;

FIGS. 81-89 depict various embodiments of battery chargers/dockingstations;

FIGS. 90A-90C are various views of a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIGS. 91A-91I are various views of a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIGS. 92A-92I are various views of a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIGS. 93A-93I are various views of a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIGS. 94A-94F are various views of a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIG. 95 is an exploded view of a volume sensor assembly included withinthe infusion pump assembly of FIG. 1;

FIG. 96 is a diagrammatic view of a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIG. 97 is a two-dimensional graph of a performance characteristic ofthe volume sensor assembly of FIG. 96;

FIG. 98 is a two-dimensional graph of a performance characteristic ofthe volume sensor assembly of FIG. 96;

FIG. 99 is a two-dimensional graph of a performance characteristic ofthe volume sensor assembly of FIG. 96;

FIG. 100 is a diagrammatic view of a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIG. 101 is a two-dimensional graph of a performance characteristic ofthe volume sensor assembly of FIG. 100;

FIG. 102 is a two-dimensional graph of a performance characteristic ofthe volume sensor assembly of FIG. 100;

FIG. 103 is a diagrammatic view of a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIG. 104 is a two-dimensional graph of a performance characteristic of avolume sensor assembly included within the infusion pump assembly ofFIG. 1;

FIG. 105 is a two-dimensional graph of a performance characteristic of avolume sensor assembly included within the infusion pump assembly ofFIG. 1;

FIG. 106 is a two-dimensional graph of a performance characteristic of avolume sensor assembly included within the infusion pump assembly ofFIG. 1;

FIG. 107 is a two-dimensional graph of a performance characteristic of avolume sensor assembly included within the infusion pump assembly ofFIG. 1;

FIG. 108 is a two-dimensional graph of a performance characteristic of avolume sensor assembly included within the infusion pump assembly ofFIG. 1;

FIG. 109 is a diagrammatic view of a control model for a volume sensorassembly included within the infusion pump assembly of FIG. 1;

FIG. 110 is a diagrammatic view of an electrical control assembly forthe volume sensor assembly included within the infusion pump assembly ofFIG. 1;

FIG. 111 is a diagrammatic view of a volume controller for the volumesensor assembly included within the infusion pump assembly of FIG. 1;

FIG. 112 is a diagrammatic view of a feed forward controller of thevolume controller of FIG. 111;

FIGS. 113-114 diagrammatically depicts an implementation of an SMAcontroller of the volume controller of FIG. 111;

FIG. 114A-114B is an alternate implementation of an SMA controller;

FIG. 115 diagrammatically depicts a multi-processor controlconfiguration that may be included within the infusion pump assembly ofFIG. 1;

FIG. 116 is a diagrammatic view of a multi-processor controlconfiguration that may be included within the infusion pump assembly ofFIG. 1;

FIG. 117A-117B diagrammatically depicts multi-processor functionality;

FIG. 118 diagrammatically depicts multi-processor functionality;

FIG. 119 diagrammatically depicts multi-processor functionality;

FIGS. 120A-120E graphically depicts various software layers;

120B-120C depict various state diagrams;

120D graphically depicts device interaction;

120E graphically depicts device interaction;

FIG. 121 diagrammatically depicts a volume sensor assembly includedwithin the infusion pump assembly of FIG. 1;

FIG. 122 diagrammatically depicts an inter-connection of the varioussystems of the infusion pump assembly of FIG. 1;

FIG. 123 diagrammatically depicts basal-bolus infusion events;

FIG. 124 diagrammatically depicts basal-bolus infusion events;

FIGS. 125A-125G depicts a hierarchial state machine;

FIG. 126A-126M depicts a hierarchial state machine;

FIG. 127 is an exemplary diagram of a split ring resonator antenna;

FIG. 128 is an exemplary diagram of a medical device configured toutilize a split ring resonator antenna;

FIG. 129 is an exemplary diagram of a split ring resonator antenna andtransmission line from a medical infusion device;

FIG. 130 is a graph of the return loss of a split ring resonator antennaprior to contact with human skin;

FIG. 130A is a graph of the return loss of a split ring resonatorantenna during contact with human skin;

FIG. 131 is an exemplary diagram of a split ring resonator antennaintegrated into a device which operates within close proximity todielectric material;

FIG. 132 is a diagram of the dimensions of the inner and outer portionof the exemplary embodiment;

FIG. 133 is a graph of the return loss of a non-split ring resonatorantenna prior to contact with human skin; and

FIG. 133A is a graph of the return loss of a non-split ring resonatorantenna during contact with human skin.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-3, an infusion pump assembly 100 may include areusable housing assembly 102. Reusable housing assembly 102 may beconstructed from any suitable material, such as a hard or rigid plastic,that will resist compression. For example, use of durable materials andparts may improve quality and reduce costs by providing a reusableportion that lasts longer and is more durable, providing greaterprotection to components disposed therein.

Reusable housing assembly 102 may include mechanical control assembly104 having a pump assembly 106 and at least one valve assembly 108.Reusable housing assembly 102 may also include electrical controlassembly 110 configured to provide one or more control signals tomechanical control assembly 104 and effectuate the basal and/or bolusdelivery of an infusible fluid to a user. Disposable housing assembly114 may include valve assembly 108 which may be configured to controlthe flow of the infusible fluid through a fluid path. Reusable housingassembly 102 may also include pump assembly 106 which may be configuredto pump the infusible fluid from the fluid path to the user.

Electrical control assembly 110 may monitor and control the amount ofinfusible fluid that has been and/or is being pumped. For example,electrical control assembly 110 may receive signals from volume sensorassembly 148 and calculate the amount of infusible fluid that has justbeen dispensed and determine, based upon the dosage required by theuser, whether enough infusible fluid has been dispensed. If enoughinfusible fluid has not been dispensed, electrical control assembly 110may determine that more infusible fluid should be pumped. Electricalcontrol assembly 110 may provide the appropriate signal to mechanicalcontrol assembly 104 so that any additional necessary dosage may bepumped or electrical control assembly 110 may provide the appropriatesignal to mechanical control assembly 104 so that the additional dosagemay be dispensed with the next dosage. Alternatively, if too muchinfusible fluid has been dispensed, electrical control assembly 110 mayprovide the appropriate signal to mechanical control assembly 104 sothat less infusible fluid may be dispensed in the next dosage.

Mechanical control assembly 104 may include at least one shape-memoryactuator 112. Pump assembly 106 and/or valve assembly 108 of mechanicalcontrol assembly 104 may be actuated by at least one shape-memoryactuator, e.g., shape-memory actuator 112, which may be a shape-memorywire in wire or spring configuration. Shape memory actuator 112 may beoperably connected to and activated by electrical control assembly 110,which may control the timing and the amount of heat and/or electricalenergy used to actuate mechanical control assembly 104. Shape memoryactuator 112 may be, for example, a conductive shape-memory alloy wirethat changes shape with temperature. The temperature of shape-memoryactuator 112 may be changed with a heater, or more conveniently, byapplication of electrical energy. Shape memory actuator 112 may be ashape memory wire constructed of nickel/titanium alloy, such as NITINOL™or FLEXINOL®.

Infusion pump assembly 100 may include a volume sensor assembly 148configured to monitor the amount of fluid infused by infusion pumpassembly 100. For example, volume sensor assembly 148 may employ, forexample, acoustic volume sensing. Acoustic volume measurement technologyis the subject of U.S. Pat. Nos. 5,575,310 and 5,755,683 assigned toDEKA Products Limited Partnership, as well as U.S. patent applicationPublication Nos. US 2007/0228071 A1, US 2007/0219496 A1, US 2007/0219480A1, US 2007/0219597 A1, the entire disclosures of all of which areincorporated herein by reference. Other alternative techniques formeasuring fluid flow may also be used; for example, Doppler-basedmethods; the use of Hall-effect sensors in combination with a vane orflapper valve; the use of a strain beam (for example, related to aflexible member over a fluid reservoir to sense deflection of theflexible member); the use of capacitive sensing with plates; or thermaltime of flight methods. One such alternative technique is disclosed inU.S. patent application Ser. No. 11/704,899, entitled Fluid DeliverySystems and Methods, filed 9 Feb. 2007, the entire disclosure of whichis incorporated herein by reference. Infusion pump assembly 100 may beconfigured so that the volume measurements produced by volume sensorassembly 148 may be used to control, through a feedback loop, the amountof infusible fluid that is infused into the user.

Infusion pump assembly 100 may further include a disposable housingassembly 114. For example, disposable housing assembly 114 may beconfigured for a single use or for use for a specified period of time,e.g., three days or any other amount of time. Disposable housingassembly 114 may be configured such that any components in infusion pumpassembly 100 that come in contact with the infusible fluid are disposedon and/or within disposable housing assembly 114. For example, a fluidpath or channel including a reservoir, may be positioned withindisposable housing assembly 114 and may be configured for a single useor for a specified number of uses before disposal. The disposable natureof disposable housing assembly 114 may improve sanitation of infusionpump assembly 100.

Referring also to FIG. 4, disposable housing assembly 114 may beconfigured to releasably engage reusable housing assembly 102, andincludes a cavity 116 that has a reservoir 118 for receiving aninfusible fluid (not shown), e.g., insulin. Such releasable engagementmay be accomplished by a screw-on, a twist-lock or a compression fitconfiguration, for example. Disposable housing assembly 114 and/orreusable housing assembly 102 may include an alignment assemblyconfigured to assist in aligning disposable housing assembly 114 andreusable housing assembly 102 for engagement in a specific orientation.Similarly, base nub 120 and top nub 122 may be used as indicators ofalignment and complete engagement.

Cavity 116 may be at least partially formed by and integral todisposable housing assembly 114. Cavity 116 may include a membraneassembly 124 for at least partially defining reservoir 118. Reservoir118 may be further defined by disposable housing assembly 114, e.g., bya recess 126 formed in base portion 128 of disposable housing assembly114. For example, membrane assembly 124 may be disposed over recess 126and attached to base portion 128, thereby forming reservoir 118.Membrane assembly 124 may be attached to base portion 128 byconventional means, such as gluing, heat sealing, and/or compressionfitting, such that a seal 130 is formed between membrane assembly 124and base portion 128. Membrane assembly 124 may be flexible and thespace formed between membrane assembly 124 and recess 126 in baseportion 128 may define reservoir 118. Reservoir 118 may benon-pressurized and in fluid communication with a fluid path (notshown). Membrane assembly 124 may be at least partially collapsible andcavity 116 may include a vent assembly, thereby advantageouslypreventing the buildup of a vacuum in reservoir 118 as the infusiblefluid is delivered from reservoir 118 to the fluid path. In a preferredembodiment, membrane assembly 124 is fully collapsible, thus allowingfor the complete delivery of the infusible fluid. Cavity 116 may beconfigured to provide sufficient space to ensure there is always someair space even when reservoir 118 is filled with infusible fluid.

The membranes and reservoirs described herein may be made from materialsincluding but not limited to silicone, NITRILE, and any other materialhaving desired resilience and properties for functioning as describedherein. Additionally, other structures could serve the same purpose.

The use of a partially collapsible non pressurized reservoir mayadvantageously prevent the buildup of air in the reservoir as the fluidin the reservoir is depleted. Air buildup in a vented reservoir couldprevent fluid egress from the reservoir, especially if the system istilted so that an air pocket intervenes between the fluid contained inthe reservoir and the septum of the reservoir. Tilting of the system isexpected during normal operation as a wearable device.

Reservoir 118 may be conveniently sized to hold an insulin supplysufficient for delivery over one or more days. For example, reservoir118 may hold about 1.00 to 3.00 ml of insulin. A 3.00 ml insulinreservoir may correspond to approximately a three day supply for about90% of potential users. In other embodiments, reservoir 118 may be anysize or shape and may be adapted to hold any amount of insulin or otherinfusible fluid. In some embodiments, the size and shape of cavity 116and reservoir 118 is related to the type of infusible fluid that cavity116 and reservoir 118 are adapted to hold.

Disposable housing assembly 114 may include a support member 132 (FIG.3) configured to prevent accidental compression of reservoir 118.Compression of reservoir 118 may result in an unintentional dosage ofinfusible fluid being forced through the fluid path to the user. In apreferred embodiment, reusable housing assembly 102 and disposablehousing assembly 114 may be constructed of a rigid material that is noteasily compressible. However, as an added precaution, support member 132may be included within disposable housing assembly 114 to preventcompression of infusion pump assembly 100 and cavity 116 therein.Support member 132 may be a rigid projection from base portion 128. Forexample, support member 132 may be disposed within cavity 116 and mayprevent compression of reservoir 118.

As discussed above, cavity 116 may be configured to provide sufficientspace to ensure there is always some air space even when reservoir 118is filled with infusible fluid. Accordingly, in the event that infusionpump assembly 100 is accidentally compressed, the infusible fluid maynot be forced through cannula assembly 136 (e.g., shown in FIG. 9).

Cavity 116 may include a septum assembly 146 (FIG. 3) configured toallow reservoir 118 to be filled with the infusible fluid. Septumassembly 146 may be a conventional septum made from rubber or plasticand have a one-way fluid valve configured to allow a user to fillreservoir 118 from a syringe or other filling device. In someembodiments, septum 146 may be located on the top of membrane assembly124. In these embodiments, cavity 116 may include a support structure(e.g., support member 132 in FIG. 3) for supporting the area about theback side of the septum so as to maintain the integrity of the septumseal when a needle is introducing infusible fluid into cavity 116. Thesupport structure may be configured to support the septum while stillallowing the introduction of the needle for introducing infusible fluidinto cavity 116.

Infusion pump assembly 100 may include an overfill prevention assembly(not shown) that may e.g., protrude into cavity 116 and may e.g.,prevent the overfilling of reservoir 118.

In some embodiments, reservoir 118 may be configured to be filled aplurality of times. For example, reservoir 118 may be refillable throughseptum assembly 146. As infusible fluid may be dispensed to a user,electronic control assembly 110 may monitor the fluid level of theinfusible fluid in reservoir 118. When the fluid level reaches a lowpoint, electronic control assembly 110 may provide a signal, such as alight or a vibration, to the user that reservoir 118 needs to berefilled. A syringe, or other filling device, may be used to fillreservoir 118 through septum 146.

Reservoir 118 may be configured to be filled a single time. For example,a refill prevention assembly (not shown) may be utilized to prevent therefilling of reservoir 118, such that disposable housing assembly 114may only be used once. The refill prevention assembly (not shown) may bea mechanical device or an electro-mechanical device. For example,insertion of a syringe into septum assembly 146 for filling reservoir118 may trigger a shutter to close over septum 146 after a singlefilling, thus preventing future access to septum 146. Similarly, asensor may indicate to electronic control assembly 110 that reservoir118 has been filled once and may trigger a shutter to close over septum146 after a single filling, thus preventing future access to septum 146.Other means of preventing refilling may be utilized and are consideredto be within the scope of this disclosure.

As discussed above, disposable housing assembly 114 may include septumassembly 146 that may be configured to allow reservoir 118 to be filledwith the infusible fluid. Septum assembly 146 may be a conventionalseptum made from rubber or any other material that may function as aseptum, or, in other embodiments, septum assembly 146 may be, but is notlimited to, a plastic, or other material, one-way fluid valve. Invarious embodiments, including the exemplary embodiment, septum assembly146 is configured to allow a user to fill reservoir 118 from a syringeor other filling device. Disposable housing assembly 114 may include aseptum access assembly that may be configured to limit the number oftimes that the user may refill reservoir 118.

For example and referring also to FIGS. 5A-5C, septum access assembly152 may include shutter assembly 154 that may be held in an “open”position by a tab assembly 156 that is configured to fit within a slotassembly 158. Upon penetrating septum 146 with filling syringe 160,shutter assembly 154 may be displaced downward, resulting in tabassembly 156 disengaging from slot assembly 158. Once disengaged, springassembly 162 may displace shutter assembly 154 in the direction of arrow164, resulting in septum 146 no longer being accessible to the user.

Referring also to FIG. 6A, an alternative-embodiment septum accessassembly 166 is shown in the “open” position. In a fashion similar tothat of septum access assembly 152, septum access assembly 166 includesshutter assembly 168 and spring assembly 170.

Referring also to FIG. 6B, an alternative-embodiment of septum accessassembly 172 is shown in the “open” position where tab 178 may engageslot 180. In a fashion similar to that of septum access assembly 166,septum access assembly 172 may include shutter assembly 174 and springassembly 176. Once shutter assembly 172 moves to the “closed” position(e.g., which may prevent further access of septum 146 by the user), tab178 may at least partially engage slot 180 a. Engagement between tab 178and slot 180 a may lock shutter assembly 172 in the “closed” position toinhibit tampering and reopening of shutter assembly 172. Spring tab 182of shutter assembly 172 may bias tab 178 into engagement with slot 180a.

However, in various embodiments, septum access assemblies may not beactuated linearly. For example and referring also to FIGS. 7A-7B, thereis shown alternative embodiment septum access assembly 184 that includesshutter assembly 186 that is configured to pivot about axis 188. Whenpositioned in the open position (as shown in FIG. 7A), septum 146 may beaccessible due to passage 190 (in shutter assembly 186) being alignedwith passage 192 in e.g., a surface of disposable housing assembly 114.However, in a fashion similar to septum access assemblies 166, 172, uponpenetrating septum 146 with filling syringe 160 (See FIG. 6B), shutterassembly 186 may be displaced in a clockwise fashion, resulting inpassage 190 (in shutter assembly 186) no longer being aligned withpassage 192 in e.g., a surface of disposable housing assembly 114, thuspreventing access to septum 146.

Referring also to FIGS. 8A-8B, an alternative-embodiment septum accessassembly 194 is shown. In a fashion similar to that of septum accessassemblies 166, 172, septum access assembly 194 includes shutterassembly 196 and spring assembly 198 that is configured to bias shutterassembly 196 in the direction of arrow 200. Filling assembly 202 may beused to fill reservoir 118. Filling assembly 202 may include shutterdisplacement assembly 204 that may be configured to displace shutterassembly 196 in the direction of arrow 206, which in turn aligns passage208 in shutter assembly 196 with septum 146 and passage 210 in septumaccess assembly 194, thus allowing filling syringe assembly 212 topenetrate septum 146 and fill reservoir 118.

Infusion pump assembly 100 may include a sealing assembly 150 (FIG. 3)configured to provide a seal between reusable housing assembly 102 anddisposable housing assembly 114. For example, when reusable housingassembly 102 and disposable housing assembly 114 are engaged by e.g.rotational screw-on engagement, twist-lock engagement or compressionengagement, reusable housing assembly 102 and disposable housingassembly 114 may fit together snuggly, thus forming a seal. In someembodiments, it may be desirable for the seal to be more secure.Accordingly, sealing assembly 150 may include an o-ring assembly (notshown). Alternatively, sealing assembly 150 may include an over moldedseal assembly (not shown). The use of an o-ring assembly or an overmolded seal assembly may make the seal more secure by providing acompressible rubber or plastic layer between reusable housing assembly102 and disposable housing assembly 114 when engaged thus preventingpenetration by outside fluids. In some instances, the o-ring assemblymay prevent inadvertent disengagement. For example, sealing assembly 150may be a watertight seal assembly and, thus, enable a user to wearinfusion pump assembly 100 while swimming, bathing or exercising.

Referring also to FIG. 9, infusion pump assembly 100 may include anexternal infusion set 134 configured to deliver the infusible fluid to auser. External infusion set 134 may be in fluid communication withcavity 118, e.g. by way of the fluid path. External infusion set 134 maybe disposed adjacent to infusion pump assembly 100. Alternatively,external infusion set 134 may be configured for application remote frominfusion pump assembly 100, as discussed in greater detail below.External infusion set 134 may include a cannula assembly 136, which mayinclude a needle or a disposable cannula 138, and tubing assembly 140.Tubing assembly 140 may be in fluid communication with reservoir 118,for example, by way of the fluid path, and with cannula assembly 138 forexample, either directly or by way of a cannula interface 142.

External infusion set 134 may be a tethered infusion set, as discussedabove regarding application remote from infusion pump assembly 100. Forexample, external infusion set 134 may be in fluid communication withinfusion pump assembly 100 through tubing assembly 140, which may be ofany length desired by the user (e.g., 3-18 inches). Though infusion pumpassembly 100 may be worn on the skin of a user with the use of adhesivepatch 144, the length of tubing assembly 140 may enable the user toalternatively wear infusion pump assembly 100 in a pocket. This may bebeneficial to users whose skin is easily irritated by application ofadhesive patch 144. Similarly, wearing and/or securing infusion pumpassembly 100 in a pocket may be preferable for users engaged in physicalactivity.

In addition to/as an alternative to adhesive patch 144, a hook and loopfastener system (e.g. such as hook and loop fastener systems offered byVelcro USA Inc. of Manchester, N.H.) may be utilized to allow for easyattachment/removal of an infusion pump assembly (e.g., infusion pumpassembly 100) from the user. Accordingly, adhesive patch 144 may beattached to the skin of the user and may include an outward facing hookor loop surface. Additionally, the lower surface of disposable housingassembly 114 may include a complementary hook or loop surface. Dependingupon the separation resistance of the particular type of hook and loopfastener system employed, it may be possible for the strength of thehook and loop connection to be stronger than the strength of theadhesive to skin connection. Accordingly, various hook and loop surfacepatterns may be utilized to regulate the strength of the hook and loopconnection.

Referring also to FIGS. 10A-10E, five examples of such hook and loopsurface patterns are shown. Assume for illustrative purposes that theentire lower surface of disposable housing assembly 114 is covered in a“loop” material. Accordingly, the strength of the hook and loopconnection may be regulated by varying the pattern (i.e., amount) of the“hook” material present on the surface of adhesive patch 144. Examplesof such patterns may include but are not limited to: a singular outercircle 220 of “hook” material (as shown in FIG. 10A); a plurality ofconcentric circles 222, 224 of “hook” material (as shown in FIG. 10B); aplurality of radial spokes 226 of “hook” material (as shown in FIG.10C); a plurality of radial spokes 228 of “hook” material in combinationwith a single outer circle 230 of “hook” material (as shown in FIG.10D); and a plurality of radial spokes 232 of “hook” material incombination with a plurality of concentric circles 234, 236 of “hook”material (as shown in FIG. 10E).

Additionally and referring also to FIG. 11A, in one exemplary embodimentof the above-described infusion pump assembly, infusion pump assembly100′ may be configured via a remote control assembly 300. In thisparticular embodiment, infusion pump assembly 100′ may include telemetrycircuitry (not shown) that allows for communication (e.g., wired orwireless) between infusion pump assembly 100′ and e.g., remote controlassembly 300, thus allowing remote control assembly 300 to remotelycontrol infusion pump assembly 100′. Remote control assembly 300 (whichmay also include telemetry circuitry (not shown) and may be capable ofcommunicating with infusion pump assembly 100′) may include displayassembly 302 and input assembly 304. Input assembly 304 may includeslider assembly 306 and switch assemblies 308, 310. In otherembodiments, the input assembly may include a jog wheel, a plurality ofswitch assemblies, or the like.

Remote control assembly 300 may include the ability to pre-program basalrates, bolus alarms, delivery limitations, and allow the user to viewhistory and to establish user preferences. Remote control assembly 300may also include a glucose strip reader.

During use, remote control assembly 300 may provide instructions toinfusion pump assembly 100′ via wireless communication channel 312established between remote control assembly 300 and infusion pumpassembly 100′. Accordingly, the user may use remote control assembly 300to program/configure infusion pump assembly 100′. Some or all of thecommunication between remote control assembly 300 and infusion pumpassembly 100′ may be encrypted to provide an enhanced level of security.

Communication between remote control assembly 300 and infusion pumpassembly 100′ may be accomplished utilizing a standardized communicationprotocol. Further, communication between the various components includedwithin infusion pump assembly 100, 100′ may be accomplished using thesame protocol. One example of such a communication protocol is thePacket Communication Gateway Protocol (PCGP) developed by DEKA Research& Development of Manchester, N.H. As discussed above, infusion pumpassembly 100, 100′ may include electrical control assembly 110 that mayinclude one or more electrical components. For example, electricalcontrol assembly 110 may include a plurality of data processors (e.g. asupervisor processor and a command processor) and a radio processor forallowing infusion pump assembly 100, 100′ to communicate with remotecontrol assembly 300. Further, remote control assembly 300 may includeone or more electrical components, examples of which may include but arenot limited to a command processor and a radio processor for allowingremote control assembly 300 to communicate with infusion pump assembly100, 100′. A high-level diagrammatic view of one example of such asystem is shown in FIG. 11B.

Each of these electrical components may be manufactured from a differentcomponent provider and, therefore, may utilize native (i.e. unique)communication commands. Accordingly, through the use of a standardizedcommunication protocol, efficient communication between such disparatecomponents may be accomplished.

PCGP may be a flexible extendable software module that may be used onthe processors within infusion pump assembly 100, 100′ and remotecontrol assembly 300 to build and route packets. PCGP may abstract thevarious interfaces and may provide a unified application programminginterface (API) to the various applications being executed on eachprocessor. PCGP may also provide an adaptable interface to the variousdrivers. For illustrative purposes only, PCGP may have the conceptualstructure illustrated in FIG. 11C for any given processor.

PCGP may ensure data integrity by utilizing cyclic redundancy checks(CRCs). PCGP may also provide guaranteed delivery status. For example,all new messages should have a reply. If such a reply isn't sent back intime, the message may time out and PCGP may generate a negativeacknowledge reply message for the application (i.e., a NACK).Accordingly, the message-reply protocol may let the application knowwhether the application should retry sending a message.

PCGP may also limit the number of messages in-flight from a given node,and may be coupled with a flow-control mechanism at the driver level toprovide a deterministic approach to message delivery and may letindividual nodes have different quantities of buffers without droppingpackets. As a node runs out of buffers, drivers may provide backpressure to other nodes and prevent sending of new messages.

PCGP may use a shared buffer pool strategy to minimize data copies, andmay avoid mutual exclusions, which may have a small affect on the APIused to send/receive messages to the application, and a larger affect onthe drivers. PCGP may use a “Bridge” base class that provides routingand buffer ownership. The main PCGP class may be sub-classed from thebridge base class. Drivers may either be derived from a bridge class, ortalk to or own a derived bridge class.

PCGP may be designed to work in an embedded environment with or withoutan operating system by using a semaphore to protect shared data suchthat some calls can be re-entrant and run on a multiple threads. Oneillustrative example of such an implementation is shown in FIG. 11D.PCGP may operate the same way in both environments, but there may beversions of the call for specific processor types (e.g., the ARM 9/OSversion). So while the functionality may be the same, there may be anoperating system abstraction layer with slightly different callstailored for e.g., the ARM 9 Nucleus OS environment.

Referring also to FIG. 11E, PCGP may:

-   -   allow multiple Send/Reply calls to occur (on Pilot's ARM 9 on        multiple tasks re-entrant);    -   have multiple drivers running asynchronously for RX and TX on        different interfaces; and    -   provide packet ordering for send/receive, and deterministic        timeout on message send.

Each software object may ask the buffer manager for the next buffer touse, and may then give that buffer to another object. Buffers may passfrom one exclusive owner to another autonomicly, and queues may occurautomatically by ordering buffers by sequence number. When a buffer isno longer in use, the buffer may be recycled (e.g., object attempts togive the buffer to itself, or frees it for the buffer manager tore-allocate later). Accordingly, data generally doesn't need to becopied, and routing simply writes over the buffer ownership byte.

Such an implementation of PCGP may provide various benefits, examples ofwhich may include but are not limited to:

-   -   dropping a message due to lack of buffers may be impossible, as        once a message is put into a buffer, the message may live there        until it is transferred or received by the application;    -   data may not need to be copied, as offsets are used to access        driver, PCGP and payload sections of a buffer;    -   drivers may exchange ownership of message data by writing over        one byte (i.e., the buffer ownership byte);    -   there may be no need for multiple exclusions except for        re-entrant calls, as a mutual exclusion may be needed only when        a single buffer owner could simultaneously want to use a buffer        or get a new sequence number;    -   there may be fewer rules for application writers to follow to        implement a reliable system;    -   drivers may use ISR/push/pull and polled data models, as there        are a set of calls provided to push/pull data out of the buffer        management system from the drivers;    -   drivers may not do much work beyond TX and RX, as drivers may        not copy, CRC or check anything but the destination byte and CRC        and other checks may be done off of the ISR hot path later;    -   as the buffer manager may order access by sequence number, queue        ordering may automatically occur; and    -   a small code/variable foot print may be utilized; hot path code        may be small and overhead may be low.

As shown in FIG. 11F, when a message needs to be sent, the PCGP maybuild the packet quickly and may insert it into the buffer managementsystem. Once in the buffer management system, a call to“packetProcessor” may apply protocol rules and may give the messages tothe drivers/application.

To send a new message or send a reply, PCGP may:

-   -   check the call arguments to e.g., make sure the packet length is        legal, destination is ok, etc.;    -   avoid trying to send a message across a link that is down unless        the down link is the radio node, which may allow PCGP to be used        by the radio processors to establish a link, pair, etc. and may        notify the application when PCGP is trying to talk across a link        that is not functional (instead of timing out);    -   obtain a sequence number for a new message or utilize an        existing sequence number for an existing message;    -   build the packet, copy the payload data and write in the CRC,        wherein (from this point forward) the packet integrity may be        protected by the CRC; and    -   either give the message to the buffer manager as a reply or as a        new message, and check to see if putting this buffer into the        buffer manager would exceed the maximum number of en-queued send        messages.

Referring also to FIGS. 11G-11H, PCGP may work by doing all of the mainwork on one thread to avoid mutual exclusions, and to avoid doingconsiderable work on the send/reply or driver calls. The“packetProcessor” call may have to apply protocol rules to replies, newsent messages, and received messages. Reply messages may simply getrouted, but new messages and received messages may have rules forrouting the messages. In each case, the software may loop while amessage of the right type is available to apply protocol rules until itcannot process the packets.

Sending a new message may conform to the following rules:

-   -   only two messages may be allowed “in-flight” on the network; and    -   enough data about an in-flight message may be stored to match        the response and handle timeout.

Receiving a message may conform to the following rules:

-   -   responses that match may clear out the “in-flight” information        slot so a new packet can be sent;    -   responses that do not match may be dropped;    -   new messages may be for the protocol (e.g., getting/clearing        network statistics for this node);    -   to receive a message, the buffer may be given up to the        application and may use a call back; and    -   the buffer may be freed or left owned by the application.

Accordingly, PCGP may be configured such that:

-   -   the call back function may copy the payload data out or may use        it completely before returning;    -   the call back function owns the buffer and may reference the        buffer and the buffer's payload by the payload address, wherein        the message may be processed later;    -   applications may poll the PCGP system for received messages; and    -   applications may use the call back to set an event and then poll        for received messages.

The communication system may have a limited number of buffers. When PCGPruns out of buffers, drivers may stop receiving new packets and theapplication may be told that the application cannot send new packets. Toavoid this and maintain optimal performance, the application may try toperform one or more procedures, examples of which may include but arenot limited to:

-   -   a) The application should keep PCGP up to date with radio        status: Specifically, if the link goes down and PCGP doesn't        know, PCGP may accept and queue new messages to send (or not        timeout messages optimally), which may jam the send queue and        delay the application from using the link optimally.    -   b) The application should call “decrement timeouts” regularly:        Optimally, every 20-100 milliseconds unless the processor is        asleep. In general, a message moves fast (milliseconds) slow        (seconds) or not at all. Timeouts are an attempt to remove        “in-flight” messages that should be dropped to free up buffers        and bandwidth. Doing this less often may delay when a new        message gets sent, or when the application can queue a new        message.    -   c) The application should ask PCGP if it has work to do that is        pending before going to sleep: If PCGP has nothing to do, driver        activity may wake up the system and thus PCGP, and then PCGP        won't need a call to “packetProcessor” or “decrement timeouts”        until new packets enter the system. Failure to do this may cause        messages that could have been sent/forwarded/received        successfully to be dropped due to a timeout condition.    -   d) The application should not hold onto received messages        indefinitely: The message system relies on prompt replies. If        the application is sharing PCGP buffers, then holding onto a        message means holding onto a PCGP buffer. The receiving node        doesn't know if the sending node has timeout configured for slow        or fast radio. This means when a node receives a message it        should assume the network's fast timeout speed.    -   e) The application should call the “packetProcessor” often: The        call may cause new messages queued by the application to get        sent and may handle receipt of new messages. The call may also        cause buffers to re-allocate and calling it infrequently may        delay message traffic.

As shown in FIG. 111, at some point the RX driver may be asked toreceive a message from the other side of the interface. To ensure amessage does not get dropped, the RX driver may ask the buffer managerif there is an available buffer for storing a new message. The drivermay then ask for a buffer pointer and may start filling the buffer withreceived data. When a complete message is received, the RX driver maycall a function to route the packet. The route function may examine thedestination byte in the packet header and may change the owner to eitherthe other driver, or the application, or may detect that the packet isbad and may drop the packet by freeing the buffer.

PCGP RX overhead may consist of asking for the next available buffer andcalling the route function. An example of code that performs such afunction is as follows:

@ Receive request uint8 i=0,  *p; if (Bridge::canReceiveFlowControl( ) ){   p = Bridge::nextBufferRx( );   while (not done)  { p[i] = the nextbyte; }   Bridge::route(p); }

A driver may perform a TX by asking the buffer manager for the pointerto the next buffer to send. The TX driver may then ask the other side ofthe interface if it can accept a packet. If the other side denies thepacket, the TX driver may do nothing to the buffer, as its status hasnot changed. Otherwise, the driver may send the packet and mayrecycle/free the buffer. An example of code that performs such afunction is as follows:

uint8 *p = Bridge::nextBufferTX( ); if (p != (uint8 *)0) {   send thebuffer p;   Bridge::recycle(p); }

To avoid forwarding packets that are past the maximum message systemtimeout time, asking for the nextBuffer may call theBufferManager::first(uint8 owner) function that may scan for buffers tofree. Accordingly, full TX buffers with no hope of making a timeout maybe freed on the thread that owns the buffer. A bridge that is doing TX(i.e., while looking for the next TX buffer) may free all of the TXbuffers that are expired before receiving the next TX buffer forprocessing.

As shown in FIG. 11J-11L, during the buffer allocation process, buffersmarked free may be transferred to the drivers to receive new packets, orto PCGP to receive new payloads for TX. Allocation from “free” may bedone by the “packetProcessor” function. The number of sends and receivesbetween “packetProcessor” calls may dictate how many LT_Driver_RX,GT_Driver_RX and PCGP_Free buffers need to be allocated. LT_Driver mayrepresent drivers that handle addresses that are less than the nodeaddress. GT_Driver may represent drivers that handle addresses that aregreater than the node address.

When a driver receives a packet, the driver may put the data into an RXbuffer that gets handed to the router. The router may then reassign thebuffer to PCGP_Receive or to the other driver's TX (not shown). If thebuffer contains obviously invalid data, the buffer may transition tofree.

After a router marks a buffer for TX, the driver may discover the bufferis TX and may send the message. After sending the message, the buffermay immediately become an RX buffer if the driver was low in RX buffers,or the buffer may be freed for re-allocation.

During the “packetProcessor” call, PCGP may process all buffers that therouter marked as PCGP_Receive. At this point, data may be acted upon, sothe CRC and other data items may be checked. If the data is corrupted, astatistic may be incremented and the buffer may be freed. Otherwise, thebuffer may be marked as owned by the application. Buffers marked asowned by the application may be either recycled for the use of PCGP orfreed for reallocation by the buffer manager.

When the application wants to send a new message, it may be done in are-entrant friendly/mutual exclusion manner. If the buffer may beallocated, PCGP may mark the buffer as busy. Once marked busy, no otherthread calling the send or reply functions may grab this buffer, as itis owned by this function call's invocation. The remainder of theprocess of error checking and building the message may be done outsidethe isolated race condition mutual exclusion guarded code. The buffermay either transition to free or may become a valid filled CRC-checkedbuffer and passed to the router. These buffers may not be routedimmediately and may be queued so that messages can be sent later(assuming that protocol rules allow). Reply messages may be markeddifferently than new send messages because reply messages may be routedwith a higher priority than regular send messages and reply messages mayhave no rules limiting how many/when they can be sent.

PCGP was designed to work with flow control, and flow control maynegotiate the transfer of messages from one node to another node so thata buffer is never dropped because the other side of an interface lacks abuffer (which may cause back pressure on the sending node).

Flow control may be apart of the shared buffer format. The first twobytes may be reserved for the driver so that the driver never needs toshift the packet bytes. Two bytes may be used so that one byte is theDMA length −1, and the second byte is to control the flow of messages.These same two bytes may be synchronizing bytes if a PCGP message istransmitted over RS232.

When a packet is “in-flight”, the packet may be in the process of beingsent by a driver on the way to its destination, being processed by thedestination, or being sent back as a response.

Typical delays are as follows:

Interface/Delay cause Delay (seconds) Notes SPI <3 Roughly 400 kbps I2C<1 Waking a CC2510 <6 ? Clock calibration, min. sleep time. Flow control<0.2 RF link 20 to 2000 Interference/ Minutes, never separation

Accordingly, messages tend to complete the round trip either: quickly(e.g., <50 ms); slowly (e.g., one or more seconds); or not at all.

PCGP may use two different times (set at initialization) for alltimeouts, one for when the RF link is in fast heartbeat mode, andanother for when the RF link is in slow mode. If a message is in-flightand the link status changes from fast to slow, the timeout may beadjusted and the difference between fast and slow may be added to thetime-to-live counter for the packet. No additional transitions back andforth may affect the time-to-live time for the message.

There is a second timeout that may be twice as long as the slow timeoutthat is used to monitor buffer allocation inside PCGP. Accordingly, if amessage is “stuck” inside a driver and hasn't been sent due to e.g.,flow control or hardware damage, the buffer may be freed by the buffermanager, resulting in the buffer being dropped. For a “new” message,this may mean that the packet already timed out and the application wasalready given a reply saying the message wasn't delivered, resulting inthe buffer being freed. Since the driver polls the buffer manager forbuffers that need to be sent, the buffer is freed up so that a messagethat could be sent is handed to the driver the next time that itunblocks. For a reply message, the reply may simply get dropped and thesending node may time out.

The PCGP messaging system may pass messages that contain headerinformation and payload. Outside of PCGP, the header may be a set ofdata items in a call signature. However, internal to PCGP, there may bea consistent, driver friendly byte layout. Drivers may insert byteseither into the PCGP packet or before the PCGP packet such:

-   -   DE, CA: Synch bytes for use with RS232, nominal value of 0xDE,        0xCA or 0x5A, 0xA5.    -   LD: Driver DMA length byte, equals amount driver is pushing in        this DMA transfer, which is the total size, not including the        size byte or synch bytes.    -   Cmd: Driver command and control byte used for flow control.    -   LP: PCGP packet length, always the total header+payload size in        bytes+CRC size. LD=LP+1.    -   Dst: Destination address.    -   Src: Source address    -   Cmd: Command byte    -   Scd: Sub command byte    -   AT: Application Tag is defined by the application and has no        significance to PCGP. It allows the application to attach more        information to a message e.g., the thread from which the message        originated.    -   SeqNum: thirty-two bit sequence number is incremented by PCGP        for a new message sent, guarantees the number will not wrap,        acts as a token, endianess isn't relevant.    -   CRC16: A sixteen bit CRC of the PCGP header and payload.

An example of a message with no payload, cmd=1, subcmd=2 is as follows:

0xDE, 0xCA, 0xC, 0x5, 0x14, 1, 2, 0, 0, 0, 0, 0x1, crchigh, crclow.0x0D,  cmd, 0xC, 0x5, 0x14, 1, 2, 0, 0, 0, 0, 0x1, crchigh, crclow.

There may be several advantages to this methodology, examples of whichmay include but are not limited to:

-   -   Most of our hardware DMA engines may use the first byte to        define how many additional bytes to move, so in this        methodology, drivers and PCGP may share buffers.    -   A byte may be provided right after the DMA length to pass flow        control information between drivers.    -   Driver length and “Cmd” byte may be outside the CRC region so        they may be altered by the driver, may be owned by the driver        transport mechanism, and the driver may guard for invalid        lengths.    -   There may be a separate PGCP packet length byte that is CRC        protected. Accordingly, the application may trust the that        payload length is correct.    -   The endianness of the sequence number may not be relevant, as it        is just a byte pattern that may be matched that happens to also        be a thirty-two bit integer.    -   The sequence number may be four bytes aligned to the edge of the        shared buffer pool length.    -   There may be optional RS232 synchronizing bytes so that users        may move cables around while debugging a message stream and both        sides of the interface may resynchronize.    -   The application, driver and PCGP may share buffers and may        release them by pointer.

PCGP may not be an event driven software design, but may be used inevent driven architectures by how the sub-classes are written. Data maybe exchanged between the classes conceptually (as shown in FIG.11M-11N).

Some event model in the driver may wake the driver, may receive amessage and may pass the message through the bridge into the buffermanager that routes the message to new owner of the new message (througha bridge to either a driver or PCGP).

The following summarizes some exemplary events:

Event: Possible use: Where this occurs: When a new send or reply isDecide to run Inside queued, or decTimeouts packetProcessor.PCGP::sendInternal generates a timeout reply. When a messages isreceived for Decide to run BufferManager::give PCGP. packetProcessor.When a driver has something new Wake driver for TX. BufferManager::giveto send. When a Driver RX buffer becomes Turn off flowBufferManager::give available. control.

The following illustrative example shows how the PCGP event model maywork with Nucleus to wakeup the PCGP task after every message send,reply, or decTimeout that generated a NACK:

class PcgpOS : public Pcgp {  virtual void schedulePacketProcessor(void) {   OS_EventGrp_Set(g_RCVEvGrps[EVG_RF_TASK].pEvgHandle,         RfRadioTxEvent, OS_EV_OR_NO_CLEAR);  }  }

The following is a pseudo code driver that is event based, illustratinghow driver events work. The Driver subclasses Bridge and overrideshasMessagesToSend and flowControlTurnedOff to schedule the TX and RXfunctions to run if they aren't already running.

class SPI_Driver : public Bridge {  virtual void hasMessagesToSend( )  {  Trigger_ISR(TX_ISR, this);  }  virtual void flowControlTurnedOff( )  {  Trigger_ISR(RX_ISR, this);  }  static void TX_RetryTimer( )  {  Trigger_ISR(TX_ISR, this);  }  static void TX_ISR(Bridge *b)  {  DisableISRs( );   do   {    uint8 *p = b->nextBufferTX( );    if (p ==null) break;    if (b->_bufferManager->bufferTimedOut(p)==false)    {    if (OtherSideSPI_FlowControl( ) == false)     {      TriggerTX_RetryTimer in 20 msec.      break;     }     send(p);    }   free(p);   } while (true) ;   EnableISRs( );  }  static voidRX_ISR(Bridge *b)  {   DisableISRs( );   do   {    uint8* p =b->nextBufferRX( );    if (p == null) break;    uint i;    while (notdone receiving)     p[i++] = getChar( );    b->route(p);   } while(true) ;   EnableISRs( );  } }

The following statistics may be supported by PCGP:

-   -   Number of packets sent;    -   Number of packets received;    -   CRC errors;    -   Timeouts; and    -   Buffer unavailable (ran out of buffers)

PCGP may be designed to run in multiple processing environments. Mostparameters may be run time configured because it facilitates testing,and any run time fine tuning for performance. Other parameters may becompile time e.g., anything that alters memory allocation must be donestatically at compile time.

The following may be compile time configuration #defines that may varywhere PCGP is implemented:

-   -   # driver bytes: may be two bytes reserved in the common buffer        scheme for the driver, but this may be a compile time option to        accommodate other drivers such as RF protocol.    -   # RX driver buffers: may be tuned to how many buffers would be        good for that processor/traffic flow, etc.    -   # PCGP RX buffers: may be tuned to how many buffers would be        good for that processor/traffic flow, etc.    -   Total # of buffers: may be tuned to how many buffers should be        at that processor.

The CRC may be used to ensure data integrity. If a CRC is invalid, itmay not be delivered to the application and the CRC error may betracked. The message may eventually timeout and may be retried by theoriginator.

Likewise, if the messaging system informs the application that a messagewas delivered when it was not, this may be a hazard to the system. TheStop Bolus Command is an example of such a command. This may bemitigated by the Request/Action sequence of messages which may berequired by the application to change therapy. The Controller mayreceive a matching command from the Pump application to consider themessage delivered.

DEKA may provide a reference way of interfacing PCGP into the Nucleus OSsystem on the ARM 9 (as shown in FIG. 10).

As shown in FIG. 11P, the pcgpOS.cpp file may instantiate a PCGP nodeinstance (Pcgp, a Bridge, etc.) and may provide through pcgpOS.h a ‘C’linkable set of function calls that provide a ‘C’ language interface tothe C++ code. This may simplify the ‘C’ code as the objects acted uponare implicit.

The following general rules may be applied:

-   -   PCGP may run on all nodes: any driver may support a generic        driver interface.    -   Race conditions may not be permitted.    -   May support half duplex on the SPI port between slave processor        and master processor.    -   Data transfer may not be attempted; as it either succeeds or        returns fail/false.    -   May require low overhead (time, processing, bandwidth wasted).    -   May support CC2510 operating at DMA (fast) SPI clock rates.

SPI flow control may prevent data from being sent if the receiving sidedoes not currently have an empty buffer to place the packet. This may beaccomplished by asking for permission to send and waiting for a responseindicating that you have been cleared to do so. There may also be a wayto tell the other side that there are currently no free buffers and thetransfer should be attempted at a later time.

All transmission may begin with a length byte that indicates the numberof bytes to be sent, not including the length byte itself. Following thelength may be a single byte indicating the command being sent.

The actual transmission of a packet may be the length of packet plus onefor the command byte, followed by the command byte for a messageappended and finally the packet itself.

In addition to the command bytes that will be sent, an additionalhardware line called the FlowControl line may be added to thetraditional four SPI signals. The purpose of this line is to allow theprotocol to run as quickly as possible without a need for preset delays.It also allows the slave processor to tell the master processor that ithas a packet waiting to be sent, thus eliminating the need for themaster processor to poll the slave processor for status.

The following exemplary command values may be used:

Commands to be sent by the master processor:

Command Value Description M_RTS 0xC1 Master is requesting to send apacket M_MSG_APPENDED 0xC2 Master is sending a packet M_CTS 0xC3 Masteris tell slave it is Cleared to Send M_ERROR 0xC4 An Error condition hasbeen encounteredCommands to be sent by the slave processor:

Command Value Description S_PREPARING_FOR_RX 0xA1 Slave is prepare thedma to receive a packet S_RX_BUFF_FULL 0xA2 Slave is currently out of RXbuffers, retry later S_MSG_APPENDED 0xA3 Slave is sending a packetS_ERROR 0xA4 An Error condition has been encountered

As illustrated in FIG. 11Q, when the slave processor has a packet tosend to the master processor, the slave processor may notify the masterprocessor (by asserting the FlowControl line) that it has a pendingpacket that is waiting to be sent. Doing so may result in an IRQ on themaster processor at which time the master processor may decide when togo retrieve the message from the slave processor. Retrieving the packetmay be delayed at the discretion of the master processor, and the masterprocessor may even decide to attempt to send a packet to the slaveprocessor before retrieving from the slave processor.

The master processor may begin the retrieval by sending the slaveprocessor M_CTS commands; this shall be repeated until the slaveprocessor responds by sending the S_MSG_APPENDED command along with thepacket itself. The FlowControl line may be cleared after the packet hasbeen sent. If a M_CTS command is received by the slave processor whenone is not expected, the M_CTS command may be ignored.

As illustrated in FIG. 11R, when the master processor has a packet tosend to the slave processor, the master processor may initiate thetransfer by sending a M_RTS command. Upon receiving the M_RTS command,if the slave processor currently has a send packet pending, the slaveprocessor will lower the FlowControl line so that it may be re-used as aCleared To Send signal. The slave processor may then tell the masterprocessor that it is in the process of preparing the SPI DMA to receivethe packet, during which time the master processor may stop clockingbytes onto the bus and may allow the slave processor to finish preparingfor the receive.

The slave processor may then indicate it is ready to receive the fullpacket by raising the FlowControl line (which is now used as the CTSsignal). Upon receiving the CTS signal, the master processor may proceedto send the M_MSG_APPENDED command along with the packet itself.

After the completion of the transfer, the slave processor may lower theFlowControl line. If a packet was pending at the start of the transfer,or a send occurred on the slave processor when the packet was beingreceived, the slave processor may reassert the FlowControl line nowindicating that it has a pending packet.

Referring again to FIG. 11A, infusion pump assembly 100, 100′ mayinclude switch assembly 318 coupled to electrical control assembly 110(FIG. 3) that may allow a user (not shown) to perform at least one, andin some embodiments, a plurality of tasks. One illustrative example ofsuch a task is the administration of a bolus dose of the infusible fluid(e.g., insulin) without the use of a display assembly. Remote controlassembly 300 may allow the user to enable/disable/configure infusionpump assembly 100, 100′ to administer the bolus dose of insulin.

Referring also to FIG. 12A, slider assembly 306 may be configured, atleast in part, to enable the user to manipulate the menu-basedinformation rendered on display assembly 302. An example of sliderassembly 306 may include a capacitive slider assembly, which may beimplemented using a CY8C21434-24LFXI PSOC offered by CypressSemiconductor of San Jose, Calif., the design an operation of which aredescribed within the “CSD User Module” published by CypressSemiconductor. For example, via slider assembly 306, the user may slidetheir finger in the direction of arrow 314, resulting in the highlightedportion of the information included within main menu 350 (shown in FIG.12A) rendered on display assembly 302 scrolling upward. Alternatively,the user may slide their finger in the direction of arrow 316, resultingin the highlighted portion of the information included within main menu350 rendered on display assembly 302 scrolling downward.

Slider assembly 306 may be configured so that the rate at which e.g. thehighlighted portion of main menu 350 scrolls “upward” or “downward”varies depending upon the displacement of the finger of the user withrespect to point of origin 320. Therefore, if the user wishes to quicklyscroll “upward”, the user may position their finger near the top ofslider assembly 306. Likewise, if the user wishes to quickly scroll“downward”, the user may position their finger near the bottom of sliderassembly 306. Additionally, if the user wishes to slowly scroll“upward”, the user may position their finger slightly “upward” withrespect to point of origin 320 Further, if the user wishes to slowlyscroll “downward”, the user may position their finger slightly“downward” with respect to point of origin 320. Once the appropriatemenu item is highlighted, the user may select the highlighted menu itemvia one or more switch assemblies 308, 310.

Referring also to FIGS. 12B-12F, assume for illustrative purposes thatinfusion pump assembly 100, 100′ is an insulin pump and the user wishesto configure infusion pump assembly 100, 100′ so that when switchassembly 318 is depressed by the user, a 0.20 unit bolus dose of insulinis administered. Accordingly, the user may use slider assembly 306 tohighlight “Bolus” within main menu 350 rendered on display assembly 302.The user may then use switch assembly 308 to select “Bolus”. Onceselected, processing logic (not shown) within remote control assembly300 may then render submenu 352 on display assembly 302 (as shown inFIG. 12B).

The user may then use slider assembly 306 to highlight “Manual Bolus”within submenu 352, which may be selected using switch assembly 308.Processing logic (not shown) within remote control assembly 300 may thenrender submenu 354 on display assembly 302 (as shown in FIG. 12C).

The user may then use slider assembly 306 to highlight “Bolus: 0.0Units” within submenu 354, which may be selected using switch assembly308. Processing logic (not shown) within remote control assembly 300 maythen render submenu 356 on display assembly 302 (as shown in FIG. 12D).

The user may then use slider assembly 306 to adjust the “Bolus” insulinamount to “0.20 units”, which may be selected using switch assembly 308.Processing logic (not shown) within remote control assembly 300 may thenrender submenu 358 on display assembly 302 (as shown in FIG. 12E).

The user 14 may then use slider assembly 306 to highlight “Confirm”,which may be selected using switch assembly 308. Processing logic (notshown) within remote control assembly 300 may then generate theappropriate signals that may be sent to the above-described telemetrycircuitry (not shown) included within remote control assembly 300. Thetelemetry circuitry (not shown) included within the remote controlassembly may then transmit, via wireless communication channel 312established between remote control assembly 300 and infusion pumpassembly 100′, the appropriate configuration commands to configureinfusion pump assembly 100′ so that whenever switch assembly 318 isdepressed by the user, a 0.20 unit bolus dose of insulin isadministered.

Once the appropriate commands are successfully transmitted, processinglogic (not shown) within remote control assembly 300 may once againrender submenu 350 on display assembly 302 (as shown in FIG. 12F).

Specifically and once programmed via remote control assembly 300, theuser may depress switch assembly 318 of infusion pump assembly 100′ toadminister the above-described 0.20 unit bolus dose of insulin. Via theabove-described menuing system included within remote control assembly300, the user may define a quantity of insulin to be administered eachtime that the user depresses switch assembly 318. While this particularexample specifies that a single depression of switch assembly 318 isequivalent to 0.20 units of insulin, this is for illustrative purposesonly and is not intended to be a limitation of this disclosure, as othervalues (e.g. 1.00 units of insulin per depression) are equallyapplicable.

Assume for illustrative purposes that the user wishes to administer a2.00 unit bolus dose of insulin. To activate the above-describe bolusdose administration system, the user may be required to press and holdswitch assembly 318 for a defined period of time (e.g. five seconds), atwhich point infusion pump assembly 100, 100′ may generate an audiblesignal indicating to the user that infusion pump assembly 100, 100′ isready to administer a bolus does of insulin via switch assembly 318.Accordingly, the user may depress switch assembly 318 ten times (i.e.,2.00 units is ten 0.20 unit doses). After each time that switch assembly318 is depressed, infusion pump assembly 100, 100′ may provide onaudible response to the user via an internal speaker/sound generationdevice (not shown). Accordingly, the user may depress switch assembly318 the first time and infusion pump assembly 100, 100′ may generate aconfirmation beep in response, thus indicating to the user that infusionpump assembly 100, 100′ received the command for (in this particularexample) 0.20 units of insulin. As the desired bolus dose is 2.00 unitsof insulin, the user may repeat this procedure nine more times in orderto effectuate a bolus dose of 2.00 units, wherein infusion pump assembly100, 100′ generates a confirmation beep after each depression of switchassembly 318.

While in this particular example, infusion pump assemblies 100, 100′ aredescribed as providing one beep after each time the user depressesswitch assembly 318, this is for illustrative purposes only and is notintended to be a limitation of this disclosure. Specifically, infusionpump assembly 100, 100′ may be configured to provide a single beep foreach defined quantity of insulin. As discussed above, a singledepression of switch assembly 318 may be equivalent to 0.20 units ofinsulin. Accordingly, infusion pump assembly 100, 100′ may be configuredto provide a single beep for each 0.10 units of insulin. Accordingly, ifinfusion pump assembly 100, 100′ is configured such that a singledepression of switch assembly 318 is equivalent to 0.20 units ofinsulin, each time switch assembly 318 is depressed, infusion pumpassembly 100, 100′ may provide the user with two beeps (i.e. one foreach 0.10 units of insulin).

Once the user has depressed switch assembly 318 on infusion pumpassembly 100′ a total of ten times, the user may simply wait forinfusion pump assembly 100, 100′ to acknowledge receipt of theinstructions to administer a 2.00 unit bolus dose of insulin (as opposedto the confirmation beep received at each depression of switch assembly318). Once a defined period of time (e.g., two seconds) passes, infusionpump assembly 100, 100′ may provide an audible confirmation to the userconcerning the quantity of units to be administered via the bolusinsulin dose that the user just requested. For example, as (in thisexample) infusion pump assembly 100, 100′ was programmed by the user sothat a single depression of switch assembly 318 is equivalent to 0.20units of insulin, infusion pump assembly 100, 100′ may beep ten times(i.e., 2.00 units is ten 0.20 unit doses).

When providing feedback to the user concerning the quantity of units tobe administered via the bolus insulin dose, infusion pump assembly 100,100′ may provide a multifrequency audible confirmation. For example andcontinuing with the above-stated example in which ten beeps are to beprovided to the user, infusion pump assembly 100, 100′ may group thebeeps into groups of five (to facilitate easier counting by the user)and the beeps within each group of five may be rendered by infusion pumpassembly 100, 100′ so that each subsequent beep has a higher frequencythan the preceding beep (in a manner similar to a musical scale).Accordingly and continuing with the above-stated example, infusion pumpassembly 100, 100′ may render a 1,000 Hz beep, followed by an 1,100 Hzbeep, followed by a 1,200 Hz beep, followed by a 1,300 Hz beep, followedby a 1,400 Hz beep (thus completing a group of five beeps), followed bya short pause, and then a 1,000 Hz beep, followed by an 1,100 Hz beep,followed by a 1,200 Hz beep, followed by a 1,300 Hz beep, followed by a1,400 Hz beep (thus completing the second group of five beeps).According to various additional/alternative embodiments themultifrequency audible confirmation may utilize various numbers of tonesincrementing in frequency. For example, an embodiment may utilize twentydifferent tones incrementing in frequency. However, the number of tonesshould not be construed as a limitation of the present disclosure asnumber of tones may vary according to design criteria and user need.

Once infusion pump assembly 100, 100′ completes the rendering of themultifrequency audible confirmation (i.e. the ten beeps describedabove), the user may, within a defined period of time (e.g. twoseconds), depress switch assembly 318 to provide a confirmation signalto infusion pump assembly 100, 100′, indicating that the multifrequencyaudible confirmation was accurate and indicative of the size of thebolus dose of insulin to be administered (i.e. 2.00 units). Uponreceiving this confirmation signal, infusion pump assembly 100, 100′ mayrender a “confirmation received” audible tone and effectuate thedelivery of (in this particular example) the 2.00 unit bolus dose ofinsulin. In the event that infusion pump assembly 100, 100′ fails toreceive the above-described confirmation signal, infusion pump assembly100, 100′ may render a “confirmation failed” audible tone and will noteffectuate the delivery of the bolus dose of insulin. Accordingly, ifthe multifrequency audible confirmation was not accurate/indicative ofthe size of the bolus dose of insulin to be administered, the user maysimply not provide the above-described confirmation signal, therebycanceling the delivery of the bolus dose of insulin.

As discussed above, in one exemplary embodiment of the above-describedinfusion pump assembly, infusion pump assembly 100′ may be used tocommunicate with a remote control assembly 300. When such a remotecontrol assembly 300 is utilized, infusion pump assembly 100′ and remotecontrol assembly 300 may routinely contact each other to ensure that thetwo devices are still in communication with each other. For example,infusion pump assembly 100′ may “ping” remote control assembly 300 toensure that remote control assembly 300 is present and active. Further,remote control assembly 300 may “ping” infusion pump assembly 100′ toensure that infusion pump assembly 100′ is still present and active. Inthe event that one of infusion pump assembly 100′ and remote controlassembly 300 fails to establish communication with the other assembly,the assembly that is unable to establish communication may sound a“separation” alarm. For example, assume that remote control assembly 300is left in the car of the user, while infusion pump assembly 100′ is inthe pocket of the user. Accordingly and after a defined period of time,infusion pump assembly 100′ may begin sounding the “separation” alarm,indicating that communication with remote control assembly 300 cannot beestablished. Using switch assembly 318, the user may acknowledge/silencethis “separation” alarm.

As the user may define and administer a bolus insulin dose via switchassembly 318 of infusion pump assembly 100′ while remote controlassembly 300 is not in communication with infusion pump assembly 100′,infusion pump assembly 100′ may store information concerning theadministered bolus insulin dose within a log file (not shown) storedwithin infusion pump assembly 100′. This log file (not shown) may bestored within nonvolatile memory (not shown) included within infusionpump assembly 100′. Upon communication being reestablished betweeninfusion pump assembly 100′ and remote control assembly 300, infusionpump assembly 100′ may provide the information concerning theadministered bolus insulin dose stored within the log file (not shown)of infusion pump assembly 100′ to remote control assembly 300.

Further, if the user anticipates separating remote control assembly 300from infusion pump assembly 100′, the user (via the above-describedmenuing system) may configure infusion pump assembly 100′ and remotecontrol assembly 300 to be in “separation” mode, thus eliminating theoccurrence of the above-described “separation” alarms. However, thedevices may continue to “ping” each other so that when they come backinto communication with each other, infusion pump assembly 100′ andremote control assembly 300 may automatically exit “separation” mode.

Further, if the user anticipates traveling in an airplane, the user (viathe above-described menuing system of remote control assembly 300) mayconfigure infusion pump assembly 100′ and remote control assembly 300 tobe in “airplane” mode, in which each of infusion pump assembly 100′ andremote control assembly 300 suspend any and all data transmissions.While in “airplane” mode, infusion pump assembly 100′ and remote controlassembly 300 may or may not continue to receive data.

Switch assembly 318 may be used to perform additional functions, suchas: checking the battery life of reusable housing assembly 102; pairingreusable housing assembly 102 with remote control assembly 300; andaborting the administration of a bolus does of infusible fluid.

Checking Battery Life:

Reusable housing assembly 102 may include a rechargeable batteryassembly that may be capable of powering infusion pump assembly 100,100′ for approximately three days (when fully charged). Such arechargeable battery assembly may have a usable life of a predeterminednumber of usable hours, for example, or years, or other predeterminedlength of usage. However, the predetermined life may depend on manyfactors, including but not limited to, one or more of the following:climate, daily usage, and number of recharges. Whenever reusable housingassembly 102 is disconnected from disposable housing assembly 114,infusion pump assembly 100, 100′ may perform a battery check on theabove-described rechargeable battery assembly whenever switch assembly318 is depressed for a defined period of time (e.g. in excess of twoseconds). In the event that the above-described rechargeable batteryassembly is determined to be charged above a desired threshold, infusionpump assembly 100, 100′ may render a “battery pass” tone. Alternatively,in the event that the above-described rechargeable battery assembly isdetermined to be charged below a desired threshold, infusion pumpassembly 100, 100′ may render a “battery fail” tone. Infusion pumpassembly 100, 100′ may include components and/or circuitry to determinewhether reusable housing assembly 102 is disconnected from disposablehousing assembly 114.

Pairing:

As discussed above and in one exemplary embodiment of theabove-described infusion pump assembly, infusion pump assembly 100′ maybe used to communicate with remote control assembly 300. In order toeffectuate communication between infusion pump assembly 100′ and remotecontrol assembly 300, a paring process may be performed. During such apairing process, one or more infusion pump assemblies (e.g. infusionpump assembly 100′) may be configured to communicate with remote controlassembly 300 and (conversely) remote control assembly 300 may beconfigured to communicate with one or more infusion pump assemblies(e.g. infusion pump assembly 100′). Specifically, the serial numbers ofthe infusion pump assemblies (e.g. infusion pump assembly 100′) may berecorded within a pairing file (not shown) included within remotecontrol assembly 300 and the serial number of remote control assembly300 may be recorded within a pairing file (not shown) included withinthe infusion pump assemblies (e.g. infusion pump assembly 100′).

According to an embodiment, in order to effectuate such a pairingprocedure, the user may simultaneously hold down one or more switchassemblies on both remote control assembly 300 and infusion pumpassembly 100′. For example, the user may simultaneously hold down switchassembly 310 included within remote control assembly 300 and switchassembly 318 included within infusion pump assembly 100′ for a definedperiod exceeding e.g. five seconds. Once this defined period is reached,one or more of remote control assembly 300 and infusion pump assembly100′ may generate an audible signal indicating that the above-describedpairing procedure has been effectuated.

According to another embodiment, prior to performing the pairingprocess, the user may uncouple reusable housing assembly 102 fromdisposable housing assembly 114. By requiring this initial step, furtherassurance is provided that an infusion pump assembly being worn by auser may not be surreptitiously paired with a remote control assembly.

Once uncoupled, the user may enter pairing mode via input assembly 304of remote control assembly 300. For example, the user may enter pairingmode on remote control assembly 300 via the above-described menuingsystem in combination with e.g., switch assembly 310. The user may beprompted on display assembly 302 of remote control assembly 300 todepress and hold switch assembly 318 on infusion pump assembly 100′.Additionally, remote control assembly 304 may switch to a low power modeto e.g., avoid trying to pair with distant infusion pump assemblies. Theuser may then depress and hold switch assembly 318 on infusion pumpassembly 100′ so that infusion pump assembly 100′ enters a receive modeand waits for a pairing command from remote control assembly 300.

Remote control assembly 300 may then transmit a pairing request toinfusion pump assembly 100′, which may be acknowledged by infusion pumpassembly 100′. Infusion pump assembly 100′ may perform a security checkon the pairing request received from remote control assembly 300 and (ifthe security check passes) infusion pump assembly 100′ may activate apump pairing signal (i.e., enter active pairing mode). Remote controlassembly 300 may perform a security check on the acknowledgment receivedfrom infusion pump assembly 100′.

The acknowledgment received from infusion pump assembly 100′ may definethe serial number of infusion pump assembly 100′ and remote controlassembly 300 may display that serial number on display assembly 302 ofremote control assembly 300. The user may be asked if they wish to pairwith the pump found. If the user declines, the pairing process may beaborted. If the user agrees to the pairing process, remote controlassembly 300 may prompt the user (via display assembly 302) to depressand hold switch assembly 318 on infusion pump assembly 100′.

The user may then depress and hold switch assembly 318 on infusion pumpassembly 100′ and depress and hold e.g. switch assembly 310 on remotecontrol assembly 300.

Remote control assembly 300 may confirm that remote switch assembly 310was held (which may be reported to infusion pump assembly 100′).Infusion pump assembly 100′ may perform a security check on theconfirmation received from remote control assembly 300 to confirm theintegrity of same. If the integrity of the confirmation received is notverified, the pairing process is aborted. If the integrity of theconfirmation received is verified, any existing remote pairconfiguration file is overwritten to reflect newly-paired remote controlassembly 300, the pump pairing completed signal is activated, and thepairing process is completed.

Additionally, infusion pump assembly 100′ may confirm that switchassembly 318 was held (which may be reported to remote control assembly300). Remote control assembly 300 may perform a security check on theconfirmation received from infusion pump assembly 100′ to confirm theintegrity of same. If the integrity of the confirmation received is notverified, the pairing process is aborted. If the integrity of theconfirmation received is verified, a pair list file within remotecontrol assembly 300 may be modified to add infusion pump assembly 100′.Typically, remote control assembly 300 may be capable of pairing withmultiple infusion pump assemblies, while infusion pump assembly 100′ maybe capable of only pairing with a single remote control assembly. Thepairing completed signal may be activated and the pairing process may becompleted.

When the pairing process is completed, one or more of remote controlassembly 300 and infusion pump assembly 100′ may generate an audiblesignal indicating that the above-described pairing procedure has beensuccessfully effectuated.

Aborting Bolus Dose:

In the event that the user wishes to cancel a bolus dose of e.g. insulinbeing administered by infusion pump assembly 100′, the user may depressswitch assembly 318 (e.g., shown in FIGS. 1 & 2) for a defined periodexceeding e.g. five seconds. Once this defined period is reached,infusion pump assembly 100′ may render an audible signal indicating thatthe above-described cancellation procedure has been effectuated.

While switch assembly 318 is shown as being positioned on the top ofinfusion pump assembly 100, 100′, this is for illustrative purposes onlyand is not intended to be a limitation of this disclosure, as otherconfigurations are possible. For example, switch assembly 318 may bepositioned about the periphery of infusion pump assembly 100, 100′.

Referring also to FIGS. 13-15, there is shown an alternative-embodimentinfusion pump assembly 400. As with pump assembly 100, 100′, infusionpump assembly 400 may include reusable housing assembly 402 anddisposable housing assembly 404.

In a fashion similar to reusable housing assembly 102, reusable housingassembly 402 may include a mechanical control assembly (that includes atleast one pump assembly and at least one valve assembly). Reusablehousing assembly 402 may also include an electrical control assemblythat is configured to provide control signals to the mechanical controlassembly and effectuate the delivery of an infusible fluid to a user.The valve assembly may be configured to control the flow of theinfusible fluid through a fluid path and the pump assembly may beconfigured to pump the infusible fluid from the fluid path to the user

In a fashion similar to disposable housing assembly 114, disposablehousing assembly 404 may be configured for a single use or for use for aspecified period of time, e.g., e.g., three days or any other amount oftime. Disposable housing assembly 404 may be configured such that anycomponents in infusion pump assembly 400 that come in contact with theinfusible fluid are disposed on and/or within disposable housingassembly 404.

In this particular embodiment of the infusion pump assembly, infusionpump assembly 400 may include switch assembly 406 positioned about theperiphery of infusion pump assembly 400. For example, switch assembly406 may be positioned along a radial edge of infusion pump assembly 400,which may allow for easier use by a user. Switch assembly 406 may becovered with a waterproof membrane configured to prevent theinfiltration of water into infusion pump assembly 400. Reusable housingassembly 402 may include main body portion 408 (housing theabove-described mechanical and electrical control assemblies) andlocking ring assembly 410 that may be configured to rotate about mainbody portion 408 (in the direction of arrow 412).

In a fashion similar to reusable housing assembly 102 and disposablehousing assembly 114, reusable housing assembly 402 may be configured toreleasably engage disposable housing assembly 404. Such releasableengagement may be accomplished by a screw-on, a twist-lock or acompression fit configuration, for example. In an embodiment in which atwist-lock configuration is utilized, the user of infusion pump assembly400 may first properly position reusable housing assembly 402 withrespect to disposable housing assembly 404 and may then rotate lockingring assembly 410 (in the direction of arrow 412) to releasably engagereusable housing assembly 402 with disposable housing assembly 404.

Through the use of locking ring assembly 410, reusable housing assembly402 may be properly positioned with respect to disposable housingassembly 404 and then releasably engaged by rotating locking ringassembly 410, thus eliminating the need to rotate reusable housingassembly 402 with respect to disposable housing assembly 404.Accordingly, reusable housing assembly 402 may be properly aligned withdisposable housing assembly 404 prior to engagement, and such alignmentmay not be disturbed during the engagement process. Locking ringassembly 410 may include a latching mechanism (not shown) that mayprevent the rotation of locking ring assembly 410 until reusable housingassembly 402 and disposable housing assembly 404 are properly positionedwith respect to each other.

Referring also to FIGS. 16-18, there is shown an alternative-embodimentinfusion pump assembly 500. As with pump assembly 100, 100′, infusionpump assembly 500 may include reusable housing assembly 502 anddisposable housing assembly 504.

In a fashion similar to reusable housing assembly 402, reusable housingassembly 502 may include a mechanical control assembly (that includes atleast one pump assembly and at least one valve assembly). Reusablehousing assembly 502 may also include an electrical control assemblythat is configured to provide control signals to the mechanical controlassembly and effectuate the delivery of an infusible fluid to a user.The valve assembly may be configured to control the flow of theinfusible fluid through a fluid path and the pump assembly may beconfigured to pump the infusible fluid from the fluid path to the user

In a fashion similar to disposable housing assembly 404, disposablehousing assembly 504 may be configured for a single use or for use for aspecified period of time, e.g., e.g., three days or any other amount oftime. Disposable housing assembly 504 may be configured such that anycomponents in infusion pump assembly 500 that come in contact with theinfusible fluid are disposed on and/or within disposable housingassembly 504.

In this particular embodiment of the infusion pump assembly, infusionpump assembly 500 may include switch assembly 506 positioned about theperiphery of infusion pump assembly 500. For example, switch assembly506 may be positioned along a radial edge of infusion pump assembly 500,which may allow for easier use by a user. Switch assembly 506 may becovered with a waterproof membrane and/or an o-ring or other sealingmechanism may be included on the stem 507 of the switch assembly 506configured to prevent the infiltration of water into infusion pumpassembly 500. However, in some embodiments, switch assembly 506 mayinclude an overmolded rubber button, thus providing functionality as awaterproof seal without the use of a waterproof membrane or an o-ring.However, in still other embodiments, the overmolded rubber button mayadditionally be covered by a waterproof membrane and/or include ano-ring. Reusable housing assembly 502 may include main body portion 508(housing the above-described mechanical and electrical controlassemblies) and locking ring assembly 510 that may be configured torotate about main body portion 508 (in the direction of arrow 512).

In a fashion similar to reusable housing assembly 402 and disposablehousing assembly 404, reusable housing assembly 502 may be configured toreleasably engage disposable housing assembly 504. Such releasableengagement may be accomplished by a screw-on, a twist-lock or acompression fit configuration, for example. In an embodiment in which atwist-lock configuration is utilized, the user of infusion pump assembly500 may first properly position reusable housing assembly 502 withrespect to disposable housing assembly 504 and may then rotate lockingring assembly 510 (in the direction of arrow 512) to releasably engagereusable housing assembly 502 with disposable housing assembly 404.

As locking ring assembly 510 included within infusion pump assembly 500may be taller (i.e., as indicated by arrow 514) than locking ringassembly 410, locking ring assembly 510 may include a passage 516through which button 506 may pass. Accordingly, when assembling reusablehousing assembly 502, locking ring assembly 510 may be installed ontomain body portion 508 (in the direction of arrow 518). Once locking ringassembly 510 is installed onto main body portion 508, one or morelocking tabs (not shown) may prevent locking ring assembly 510 frombeing removed from main body portion 508. The portion of switch assembly506 that protrudes through passage 516 may then be pressed into mainbody portion 508 (in the direction of arrow 520), thus completing theinstallation of switch assembly 506.

Although button 506 is shown in various locations on infusion pumpassembly 500, button 506, in other embodiments, may be located anywheredesirable on infusion pump assembly 500.

Through the use of locking ring assembly 510, reusable housing assembly502 may be properly positioned with respect to disposable housingassembly 504 and then releasably engaged by rotating locking ringassembly 510, thus eliminating the need to rotate reusable housingassembly 502 with respect to disposable housing assembly 504.Accordingly, reusable housing assembly 502 may be properly aligned withdisposable housing assembly 504 prior to engagement, and such alignmentmay not be disturbed during the engagement process. Locking ringassembly 510 may include a latching mechanism (not shown) that preventsthe rotation of locking ring assembly 510 until reusable housingassembly 502 and disposable housing assembly 504 are properly positionedwith respect to each other. Passage 516 may be elongated to allow forthe movement of locking ring 510 about switch assembly 506.

Referring also to FIGS. 19A-19B & 20-21, there are shown various viewsof infusion pump assembly 500, which is shown to include reusablehousing assembly 502, switch assembly 506, and main body portion 508. Asdiscussed above, main body portion 508 may include a plurality ofcomponents, examples of which may include but are not limited to volumesensor assembly 148, printed circuit board 600, vibration motor assembly602, shape memory actuator anchor 604, switch assembly 506, battery 606,antenna assembly 608, pump assembly 106, measurement valve assembly 610,volume sensor valve assembly 612 and reservoir valve assembly 614. Toenhance clarity, printed circuit board 600 has been removed from FIG.19B to allow for viewing of the various components positioned beneathprinted circuit board 600.

The various electrical components that may be electrically coupled withprinted circuit board 600 may utilize spring-biased terminals that allowfor electrical coupling without the need for soldering the connections.For example, vibration motor assembly 602 may utilize a pair ofspring-biased terminals (one positive terminal and one negativeterminal) that are configured to press against corresponding conductivepads on printed circuit board 600 when vibration motor assembly 602 ispositioned on printed circuit board 600. However, in the exemplaryembodiment, vibration motor assembly 602 is soldered directly to theprinted circuit board.

As discussed above, volume sensor assembly 148 may be configured tomonitor the amount of fluid infused by infusion pump assembly 500. Forexample, volume sensor assembly 148 may employ acoustic volume sensing,which is the subject of U.S. Pat. Nos. 5,575,310 and 5,755,683 assignedto DEKA Products Limited Partnership, as well as the U.S. patentapplication Publication Nos. US 2007/0228071 A1, US 2007/0219496 A1, US2007/0219480 A1, US 2007/0219597 A1, the entire disclosures of all ofwhich are incorporated herein by reference.

Vibration motor assembly 602 may be configured to provide avibration-based signal to the user of infusion pump assembly 500. Forexample, in the event that the voltage of battery 606 (which powersinfusion pump assembly 500) is below the minimum acceptable voltage,vibration motor assembly 602 may vibrate infusion pump assembly 500 toprovide a vibration-based signal to the user of infusion pump assembly500. Shape memory actuator anchor 604 may provide a mounting point forthe above-described shape memory actuator (e.g. shape memory actuator112). As discussed above, shape memory actuator 112 may be, for example,a conductive shape-memory alloy wire that changes shape withtemperature. The temperature of shape-memory actuator 112 may be changedwith a heater, or more conveniently, by application of electricalenergy. Accordingly, one end of shape memory actuator 112 may be rigidlyaffixed (i.e., anchored) to shape memory actuator anchor 604 and theother end of shape memory actuator 112 may be applied to e.g. a valveassembly and/or a pump actuator. Therefore, by applying electricalenergy to shape memory actuator 112, the length of shape memory actuator112 may be controlled and, therefore, the valve assembly and/or the pumpactuator to which it is attached may be manipulated.

Antenna assembly 608 may be configured to allow for wirelesscommunication between e.g. infusion pump assembly 500 and remote controlassembly 300 (FIG. 11). As discussed above, remote control assembly 300may allow the user to program infusion pump assembly 500 and e.g.configure bolus infusion events. As discussed above, infusion pumpassembly 500 may include one or more valve assemblies configured tocontrol the flow of the infusible fluid through a fluid path (withininfusion pump assembly 500) and pump assembly 106 may be configured topump the infusible fluid from the fluid path to the user. In thisparticular embodiment of infusion pump assembly 500, infusion pumpassembly 500 is shown to include three valve assemblies, namelymeasurement valve assembly 610, volume sensor valve assembly 612, andreservoir valve assembly 614.

As discussed above and referring also to FIG. 21, the infusible fluidmay be stored within reservoir 118. In order to effectuate the deliveryof the infusible fluid to the user, the processing logic (not shown)included within infusion pump assembly 500 may energize shape memoryactuator 112, which may be anchored on one end using shape memoryactuator anchor 604. Referring also to FIG. 22A, shape memory actuator112 may result in the activation of pump assembly 106 and reservoirvalve assembly 614. Reservoir valve assembly 614 may include reservoirvalve actuator 614A and reservoir valve 614B, and the activation ofreservoir valve assembly 614 may result in the downward displacement ofreservoir valve actuator 614A and the closing of reservoir valve 614B,resulting in the effective isolation of reservoir 118. Further, pumpassembly 106 may include pump plunger 106A and pump chamber 106B and theactivation of pump assembly 106 may result in pump plunger 106A beingdisplaced in a downward fashion into pump chamber 106B and thedisplacement of the infusible fluid (in the direction of arrow 616).

Volume sensor valve assembly 612 may include volume sensor valveactuator 612A and volume sensor valve 612B. Referring also to FIG. 22B,volume sensor valve actuator 612A may be closed via a spring assemblythat provides mechanical force to seal volume sensor valve 612B.However, when pump assembly 106 is activated, if the displaced infusiblefluid is of sufficient pressure to overcome the mechanical sealing forceof volume sensor valve assembly 612, the displacement of the infusiblefluid occurs in the direction of arrow 618. This may result in thefilling of volume sensor chamber 620 included within volume sensorassembly 148. Through the use of speaker assembly 622, port assembly624, reference microphone 626, spring diaphragm 628, invariable volumemicrophone 630, volume sensor assembly 148 may determine the volume ofinfusible fluid included within volume sensor chamber 620.

Referring also to FIG. 22C, once the volume of infusible fluid includedwithin volume sensor chamber 620 is calculated, shape memory actuator632 may be energized, resulting in the activation of measurement valveassembly 610, which may include measurement valve actuator 610A andmeasurement valve 610B. Once activated and due to the mechanical energyasserted on the infusible fluid within volume sensor chamber 620 byspring diaphragm 628, the infusible fluid within volume sensor chamber620 may be displaced (in the direction of arrow 634) through disposablecannula 138 and into the body of the user.

Referring also to FIG. 23, there is shown an exploded view of infusionpump assembly 500. Shape memory actuator 632 may be anchored (on a firstend) to shape memory actuator anchor 636. Additionally, the other end ofshape memory actuator 632 may be used to provide mechanical energy tovalve assembly 638, which may activate measurement valve assembly 610.Volume sensor assembly spring retainer 642 may properly position volumesensor assembly 148 with respect to the various other components ofinfusion pump assembly 500. Valve assembly 638 may be used inconjunction with shape memory actuator 112 to activate pump plunger106A. Measurement valve 610B, volume sensor valve 612B and/or reservoirvalve 614B may be self-contained valves that are configured to allow forinstallation during assembly of infusion pump assembly 500 by pressingthe valves upward into the lower surface of main body portion 508.

Referring also to FIG. 24 & FIGS. 25A-25D, there is shown amore-detailed view of pump assembly 106. Pump actuator assembly 644 mayinclude pump actuator support structure 646, bias spring 648, and leverassembly 650.

Referring also to FIGS. 26A-26B & FIGS. 27A-27B, there is shown amore-detailed view of measurement valve assembly 610. As discussedabove, valve assembly 638 may activate measurement valve assembly 610.

Referring also to FIGS. 28A-28D, infusion pump assembly 500 may includemeasurement valve assembly 610. As discussed above, valve assembly 638may be activated via shape memory actuator 632 and actuator assembly640. Accordingly, to infuse the quantity of infusible fluid storedwithin volume sensor chamber 620, shape memory actuator 632 may need toactivate valve assembly 638 for a considerable period of time (e.g. oneminute or more). As this would consume a considerable amount of powerfrom battery 606, measurement valve assembly 610 may allow for thetemporary activation of valve assembly 638, at which point measurementvalve latch 656 may prevent valve assembly 638 from returning to itsnon-activated position. Shape memory actuator 652 may be anchored on afirst end using electrical contact 654. The other end of shape memoryactuator 652 may be connected to a valve latch 656. When shape memoryactuator 652 is activated, shape memory actuator 652 may pull valvelatch 656 forward and release valve assembly 638. As such, measurementvalve assembly 610 may be activated via shape memory actuator 632. Oncemeasurement valve assembly 610 has been activated, valve latch 656 mayautomatically latch valve assembly 638 in the activated position.Actuating shape memory actuator 652 may pull valve latch 656 forward andrelease valve assembly 638. Assuming shape memory actuator 632 is nolonger activated, measurement valve assembly 610 may move to ade-activated state once valve latch 656 has released valve assembly 638.Accordingly, through the use of measurement valve assembly 610, shapememory actuator 632 does not need to be activated during the entire timethat it takes to infuse the quantity of infusible fluid stored withinvolume sensor chamber 620.

As discussed above, the above-described infusion pump assemblies (e.g.,infusion pumps assemblies 100, 100′, 400, 500) may include an externalinfusion set 134 configured to deliver the infusible fluid to a user.External infusion set 134 may include a cannula assembly 136, which mayinclude a needle or a disposable cannula 138, and tubing assembly 140.Tubing assembly 140 may be in fluid communication with reservoir 118,for example, by way of the fluid path, and with cannula assembly 138 forexample, either directly or by way of a cannula interface 142.

Referring also to FIG. 29, there is shown an alternative embodimentinfusion pump assembly 700 that is configured to store a portion oftubing assembly 140. Specifically, infusion pump assembly 700 mayinclude peripheral tubing storage assembly 702 that is configured toallow the user to wind a portion of tubing assembly 140 about theperiphery of infusion pump assembly 700 (in a manner similar to that ofa yoyo). Peripheral tubing storage assembly 702 may be positioned aboutthe periphery of infusion pump assembly 700. Peripheral tubing storageassembly 702 may be configured as an open trough into which a portion oftubing assembly 140 may be wound. Alternatively, peripheral tubingstorage assembly 702 may include one or more divider portions 704, 706that form a plurality of narrower troughs that may be sized to generatean interference fit between the walls of the narrower trough and theexterior surface of the portion of tubing 140. When peripheral tubingstorage assembly 705 includes plurality of divider portions 704, 706,the resulting narrower troughs may be wound in a spiral fashion aboutthe periphery of infusion pump assembly 700 (in a manner similar to thethread of a screw).

Referring also to FIGS. 30-31, there is shown an alternative embodimentinfusion pump assembly 750 that is configured to store a portion oftubing assembly 140. Specifically, infusion pump assembly 750 mayinclude peripheral tubing storage assembly 752 that is configured toallow the user to wind a portion of tubing assembly 140 about theperiphery of infusion pump assembly 750 (again, in a manner similar tothat of a yoyo). Peripheral tubing storage assembly 752 may bepositioned about the periphery of infusion pump assembly 750. Peripheraltubing storage assembly 752 may be configured as an open trough intowhich a portion of tubing assembly 140 is wound. Alternatively,peripheral tubing storage assembly 752 may include one or more dividerportions 754, 756 that form a plurality of narrower troughs that may besized to generate an interference fit between the walls of the narrowertrough and the exterior surface of the portion of tubing 140. Whenperipheral tubing storage assembly 752 includes plurality of dividerportions 754, 756, the resulting narrower trough may be wound in aspiral fashion about the periphery of infusion pump assembly 750 (again,in a manner similar to the thread of a screw).

Infusion pump assembly 750 may include tubing retainer assembly 758.Tubing retainer assembly 758 may be configured to releasably securetubing assembly 140 so as to prevent tubing assembly 140 from unravelingfrom around infusion pump assembly 750. In one embodiment of tubingretainer assembly 758, tubing retainer assembly 758 may include downwardfacing pin assembly 760 positioned above upward facing pin assembly 762.The combination of pin assemblies 760, 762 may define a “pinch point”through which tubing assembly 140 may be pushed. Accordingly, the usermay wrap tubing assembly 140 around the periphery of infusion pumpassembly 750, wherein each loop of tubing assembly 140 is secured withinperipheral tubing storage assembly 752 via tubing retainer assembly 758.In the event that the user wishes to lengthen the unsecured portion oftubing assembly 140, the user may release one loop of tubing assembly140 from tubing retainer assembly 758. Conversely, in the event that theuser wishes to shorten the unsecured portion of tubing assembly 140, theuser may secure one additional loop of tubing assembly 140 within tubingretainer assembly 758.

Referring also to FIGS. 32-33, there is shown an exemplary embodiment ofinfusion pump assembly 800. As with infusion pump assemblies 100, 100′,400, and 500, infusion pump assembly 800 may include reusable housingassembly 802 and disposable housing assembly 804.

With reference also to FIGS. 34A-34B, in a fashion similar to infusionpump assembly 100, reusable housing assembly 802 may be configured toreleasably engage disposable housing assembly 804. Such releasableengagement may be effectuated by a screw-on, twist-lock, or compressionfit configuration, for example. Infusion pump assembly 800 may includelocking ring assembly 806. For example, reusable housing assembly 802may be properly positioned relative to disposable housing assembly, andlocking ring assembly 806 may be rotated to releasable engage reusablehousing assembly 802 and disposable housing assembly 804.

Locking ring assembly 806 may include nub 808 that may facilitaterotation of locking ring assembly 806. Additionally, the position of nub808, e.g., relative to tab 810 of disposable housing assembly 804, mayprovide verification that reusable housing assembly 802 is fully engagedwith disposable housing assembly 804. For example, as shown in FIG. 34A,when reusable housing assembly 802 is properly aligned with disposablehousing assembly 804, nub 808 may be aligned in a first positionrelative to tab 810. Upon achieving a fully engaged condition, byrotation locking ring assembly 806, nub 808 may be aligned in a secondposition relative to tab 810, as shown in FIG. 34B.

Referring also to FIGS. 35A-35C and FIGS. 36-38A, in a fashion similarto reusable housing assembly 102, reusable housing assembly 802 mayinclude mechanical control assembly 812 (e.g., which may include valveassembly 814, shown in FIG. 36, including one or more valves and one ormore pumps for pumping and controlling the flow of the infusible fluid).Reusable housing assembly 802 may also include an electrical controlassembly 816 that may be configured to provide control signals to themechanical control assembly 812 to effectuate the delivery of aninfusible fluid to the user. Valve assembly 814 may be configured tocontrol the flow of the infusible fluid through a fluid path and thepump assembly may be configured to pump the infusible fluid from thefluid path to the user.

Mechanical control assembly 812 and electrical control assembly 816 maybe contained within a housing defined by base plate 818, body 820. Insome embodiments one or more of base plate 818 and body 820 may provideelectromagnetic shielding. In such an embodiment, the electromagneticshielding may prevent and/or reduce electromagnetic interferencereceived by electrical control assembly 816 and/or created by electricalcontrol assembly 816. Additionally/alternatively, EMI shield 822 may beincluded, as shown in FIG. 36 and FIG. 37. EMI shield 822 may provideshielding against generated and/or received electromagneticinterference.

Reusable housing assembly 802 may include a switch assembly that may beconfigured to receive user commands (e.g., for bolus delivery, pairingwith a remote control assembly, or the like). The switch assembly mayinclude button 824 that may be disposed in opening 826 of body 820. Asshown, e.g., in FIG. 35B, locking ring assembly 806 may include radialslot 828 that may be configured to allow locking ring assembly 806 to berotated relative to body 820 while still providing facile access tobutton 824.

Referring also to FIGS. 39A-39C, electrical control assembly 816 mayinclude printed circuit board 830 as well as battery 832. Printedcircuit board 830 may include the various control electronics formonitoring and controlling the amount of infusible fluid that has beenand/or is being pumped. For example, electrical control assembly 816 maymeasure the amount of infusible fluid that has just been dispensed, anddetermine, based upon the dosage required by the user, whether enoughinfusible fluid has been dispensed. If not enough infusible fluid hasbeen dispensed, electrical control assembly 816 may determine that moreinfusible fluid should be pumped. Electrical control assembly 816 mayprovide the appropriate signal to mechanical control assembly 812 sothat any additional necessary dosage may be pumped or electrical controlassembly 816 may provide the appropriate signal to mechanical controlassembly 812 so that the additional dosage may be dispensed with thenext dosage. Alternatively, if too much infusible fluid has beendispensed, electrical control assembly 816 may provide the appropriatesignal to mechanical control assembly 812 so that less infusible fluidmay be dispensed in the next dosage. Electrical control assembly 816 mayinclude one or more microprocessors. In an exemplary embodiment,electrical control assembly 816 may include three microprocessors. Oneprocessor (e.g., which may include, but is not limited to a CC2510microcontroller/RF transceiver, available from Chipcon AS, of Oslo,Norway) may be dedicated to radio communication, e.g., for communicatingwith a remote control assembly. Two additional microprocessors (exampleof which may include, but is not limited to an MSP430 microcontroller,available from Texas Instruments Inc. of Dallas, Tex.) may be dedicatedto issuing and carrying out commands (e.g., to dispense a dosage ofinfusible fluid, process feedback signals from a volume measurementdevice, and the like).

As shown in FIG. 35C, base plate 818 may provide access to electricalcontacts 834, e.g., which may be electrically coupled to electricalcontrol assembly 816 for recharging battery 832. Base plate 818 mayinclude one or more features (e.g., openings 836, 838) which may beconfigured to facilitate proper alignment with disposable housingassembly 804 by way of cooperating features (e.g., tabs) of disposablehousing assembly 804. Additionally, as shown in FIGS. 40A-40C, 41A-41B,and 42A-42C, base plate 818 may include various features for mountingvalve assembly 814 and electrical control assembly 816, as well asproviding access to disposable housing assembly 804 by valve assembly814.

Locking ring assembly 806 may include grip inserts 840, 842, e.g., whichmay include an elastomeric or textured material that may facilitategripping and twisting locking ring assembly 806, e.g., forengaging/disengaging reusable housing assembly 802 and disposablehousing assembly 804. Additionally, locking ring assembly 806 mayinclude a sensing component (e.g., magnet 844) that may interact with acomponent of reusable housing assembly 802 (e.g., a Hall Effect sensor),e.g., to provide an indication of the nature of a mating component(e.g., which in some embodiments may include, but is not limited to, oneor more of disposable housing assembly 804, a charging station, or afilling station) and/or of whether reusable housing assembly 802 isproperly engaged with the mating component. In the exemplary embodiment,a Hall Effect sensor (not shown) may be located on the pump printedcircuit board. The Hall Effect sensor may detect when the locking ringhas been rotated to a closed position. Thus, the Hall Effect sensortogether with magnet 844 may provide a system for determining whetherthe locking ring has been rotated to a closed position.

The sensing component (magnet) 844 together with the reusable housingassembly components, i.e., in the exemplary embodiment, the Hall Effectsensor, may work to provide for a determination of whether the reusablehousing assembly is properly attached to the intended component ordevice. Locking ring assembly 806 may not turn without being attached toa component, i.e., disposable housing assembly 804, a dust cover or acharger. Thus, the sensing component together with the reusable housingassembly component may function to provide many advantageous safetyfeatures to the infusion pump system. These features may include, butare not limited to, one or more of the following. Where the system doesnot detect being attached to a disposable assembly, a dust cover or acharger, the system may notify, alert or alarm the user as the reusableportion, e.g., the valves and pumping components, may be vulnerable tocontamination or destruction which may compromise the integrity of thereusable assembly. Thus, the system may provide for an integrity alarmto alert the user of potential reusable integrity threats. Also, wherethe system senses the reusable assembly is attached to a dust cover, thesystem may power off or reduce power to conserve power. This may providefor more efficient use of power where the reusable assembly is notconnecting to a component in which it needs to interact.

Reusable housing assembly 802 may attach to a number of differentcomponents, including but not limited to, a disposable housing assembly,a dust cover or a battery charger/battery charging station. In eachcase, the Hall Effect sensor may detect that the locking ring is in theclosed position, and therefore, that reusable housing assembly 802 isreleasably engaged to a disposable housing assembly, a dust cover, or abattery charger/battery charging station (or, another component). Theinfusion pump system may determine the component to which it is attachedby using the AVS system described in more detail below or by anelectronic contact. Referring now also to FIGS. 38B-38D, one embodimentof a dust cover (e.g., dust cover 839) is shown. In the exemplaryembodiment, dust cover 839 may include features 841, 843, 845, 847 suchthat the locking ring of reusable housing assembly 802 may releasablyengage dust cover 839. In addition, dust cover 839 may further includerecess region 849 for accommodating the valving and pumping features ofreusable housing assembly 804. For example, with respect to the dustcover, the AVS system may determine that a dust cover, and not adisposable housing assembly, is connected to the reusable housingassembly. The AVS system may distinguish using a look-up table or othercomparative data and comparing the measurement data with characteristicdust cover or empty disposable housing assembly data. With respect tothe battery charger, the battery charger, in the exemplary embodiments,may include electric contacts. When the reusable housing assembly isattached to the battery charger, the infusion pump assembly electronicsystem may sense that the contacts have been made, and will thusindicate that the reusable housing assembly is attached to a batterycharger.

Referring also to FIGS. 43A-45B and FIGS. 44A-44C an embodiment of valveassembly 814, which may include one or more valves and one or morepumps, is shown. As with infusion pump assemblies 100, 100′, 400, and500, valve assembly 814 may generally include reservoir valve 850,plunger pump 852, volume sensor valve 854, and measurement valve 856.Similar to the previous description, reservoir valve 850 and plungerpump 852 may be actuated by shape memory actuator 858, which may beanchored (on a first end) to shape memory actuator anchor 860.Additionally, measurement valve 856 may be actuated, via valve actuator862, by shape memory actuator 864, which may be anchored (on a firstend) to shape memory actuator anchor 866. In a similar manner asdiscussed above, measurement valve may be maintained in an open positionvia measurement valve latch assembly 868. Measurement valve 856 may bereleased via actuation of shape memory actuator 870, which may beanchored (on a first end) by shape memory actuator anchor 872. In someembodiments, shape memory actuator anchor 860 may be potted onto thereusable housing assembly. Using this process during manufacture ensuresshape memory length actuator 858 is installed and maintains the desiredlength and tension/strain.

Referring also to FIGS. 45A-45B and FIGS. 46A-46E, shape memory actuator858 (e.g., which may include one or more shape memory wires) may actuateplunger pump 852 via actuator assembly 874. Actuator assembly 874 mayinclude bias spring 876 and lever assembly 878. Actuator assembly 874may actuate both plunger pump 852 and measurement valve 850.

Referring also to FIGS. 47A-47B, measurement valve 856 may be actuatedby shape memory actuator 864, via valve actuator 862 and lever assembly878. Once actuated, measurement valve latch assembly 868 may maintainmeasurement valve 856 in an open position. Measurement valve latchassembly 868 actuated by shape memory actuator 870 to releasemeasurement valve 856, allowing it to return to a closed position.

Disposable housing assembly 804 may be configured for a single use orfor use for a specified period of time, e.g., e.g., three days or anyother amount of time. Disposable housing assembly 804 may be configuredsuch that any of the component of infusion pump assembly 800 that comein contact with the infusible fluid may be disposed on and/or withindisposable housing assembly 804. As such, the risk of contaminating theinfusible fluid may be reduced.

Referring also to FIG. 48 and FIGS. 49A-49C, disposable housing assembly804 may include base portion 900, membrane assembly 902, and top portion904. Base portion 900 may include recess 906 that together with membraneassembly 902 defines reservoir 908 for receiving an infusible fluid (notshown), e.g., insulin. Referring also to FIGS. 50A-50C, recess 906 maybe at least partially formed by and integral with base portion 900.Membrane assembly 902 may be sealingly engaged with base portion 900,e.g., by being compressively pinched between base portion 900 and topportion 904. Top portion 904 may be attached to base portion 900 byconventional means, such as gluing, heat sealing, ultrasonic welding,and compression fitting. Additionally/alternatively, membrane assembly902 may be attached to base portion 900, e.g., via gluing, ultrasonicwelding, heat sealing, and the like, to provide a seal between membraneassembly 902 and base portion 900.

Still referring to FIGS. 48 and 50A, recess 906, in the exemplaryembodiment, includes raised portion 901 which includes area 903 aboutfluid openings 905 leading to the fluid line. Raised portion 901, in theexemplary embodiment, extends about the perimeter of recess 906.However, in other embodiments, raised portion 901 may not extend theentire perimeter, but may be partially about the perimeter. Area 903about fluid openings 905 may be shaped as shown in the exemplaryembodiment, including an angled portion, which in some embodiments,includes 45 degree angles, however in other embodiments, the angle maybe greater or lesser. In some embodiments, the pump may not generate asufficient enough vacuum to collapse the reservoir so as to eliminatethe entire volume of fluid that may be stored in the reservoir. Raisedportion 901 may act to minimize wasted fluid.

Fluid openings 905, which, in the exemplary embodiment, may includethree openings, however, in other embodiments may include more openingsor fewer openings, may be surrounded by area 903 of the raised portion.In the exemplary embodiment, fluid openings 905 may be narrow in thecenter, thus creating a surface tension that may prevent the air frombeing drawn into the opening. In the exemplary embodiment, this area maybe designed to encourage any air that is present in the reservoir to bedrawn above one of fluid openings 905 rather than be pulled throughfluid openings 905 and into the fluid line. Additionally, because theremay be more than one fluid opening 905, where an air bubble is caughtabove one, the air may not prevent fluid from flowing through the othertwo openings.

Referring also to FIGS. 51A-51C, disposable housing assembly 804 mayalso include fluid pathway cover 910. Fluid pathway cover 910 may bereceived in cavity 912 formed on/within base portion 900. Fluid pathwaycover 910 may, in some embodiments, include at least a portion of one ormore channels (e.g., channel 914). The channels included in fluidpathway cover 910 may fluidly couple one or more volcano valve features(e.g. volcano valves 916) included on base portion 900. Volcano valves916 may include a protrusion having an opening extending through it.Additionally, fluid pathway cover 910 and base portion 900 may eachdefine a portion of recess (e.g., recess portions 918, 920 included inbase portion 900 and fluid pathway cover 910 respectively) for fluidlycoupling to an infusion set (e.g., including cannula 922). Cannula 922may be coupled to disposable housing assembly 804 by conventional means(e.g., gluing, heat sealing, compression fit, or the like). The fluidpathways defined by fluid pathway cover 910 and the volcano valves(e.g., volcano valves 916) of base portion 900 may define a fluidpathway between reservoir 908 and cannula 922 for the delivery of theinfusible fluid to the user via the infusion set. However, in someembodiments, fluid path cover 910 may include at least a portion of thefluid path, and in some embodiments, fluid path cover 910 may notinclude at least a portion of the fluid path. In the exemplaryembodiment, fluid pathway cover 910 may be laser welded to base portion900. However, in other embodiments, fluid pathway cover 910 may also beconnected to base portion 900 by conventional means (e.g., gluing, heatsealing, ultrasonic welding, compression fit, or the like) to achieve agenerally fluid tight seal between fluid pathway cover 910 and baseportion 900.

With reference also to FIGS. 54A-54C, disposable housing assembly 804may further include valve membrane cover 924. Valve membrane cover 924may be at least partially disposed over the volcano valves (e.g.,volcano valve 916) and pumping recess 926 included on/within baseportion 900. Valve membrane cover 924 may include a flexible material,e.g., which may be selectively engaged against the volcano valves byreservoir valve 850, volume sensor valve 854, and measurement valve 856of reusable housing assembly 802, e.g., for controlling the flow of theinfusible fluid. Additionally, valve membrane cover 924 may beresiliently deformed into pumping recess 926 by plunger pump 852 toeffectuate pumping of the infusible fluid. Valve membrane cover 924 maybe engaged between base portion 900 and top portion 904 of disposablehousing assembly 804 to form seal 928 between valve membrane cover 924and base portion 900. For example, in the exemplary embodiment, valvemembrane cover 924 may be overmolded onto base portion 900. In otherembodiment, valve membrane cover 924 may be compressively pinchedbetween base portion 900 and top portion 904 to form seal 928.Additionally/alternatively, valve membrane insert may be connected toone or more of base portion 900 and top portion 904, e.g., by gluing,heat sealing, or the like.

Referring also to FIGS. 53A-C, top portion 904 may include alignmenttabs 930, 932 that may be configured to be at least partially receivedin openings 836, 838 of base plate 818 of reusable housing assembly 802to ensure proper alignment between reusable housing assembly 802 anddisposable housing assembly 804. Additionally, top portion 904 mayinclude one or more radial tabs 934, 936, 938, 940 configured to beengaged by cooperating tabs 942, 944, 946, 948 of locking ring assembly806. The one or more radial tabs (e.g., radial tab 940) may includestops (e.g., alignment tab stop 950, which may be used for welding, it'sthe tab that fits in the recess to locate and ultrasonically weld),e.g., which may prevent further rotation of locking ring assembly 806once reusable housing assembly 802 and disposable housing assembly 804are fully engaged.

As discussed above, valve membrane insert 924 may allow for pumping andflow of the infusible fluid by reservoir valve 850, plunger pump 852,volume sensor valve 854, and measurement valve 856. Accordingly, topportion 904 may include one or more openings (e.g., openings 952, 954,956) that may expose at least a portion of valve membrane insert 924 foractuation by reservoir valve 850, plunger pump 852, volume sensor valve854, and measurement valve 856. Additionally, top portion 904 mayinclude one or more openings 958, 960, 962 which may be configured toallow the fill volume to be controlled during filling of reservoir 908,as will be discussed in greater detail below. Reservoir assembly 902 mayinclude ribs 964, 966, 968 (e.g., as shown in FIG. 52A), which may be atleast partially received in respective openings 958, 960, 962. As willbe described in greater detail below, a force may be applied to one ormore of ribs 964, 966, 968 to, at least temporarily, reduce the volumeof reservoir 908.

In some embodiments, it may be desirable to provide a seal betweenreusable housing assembly 802 and disposable housing assembly 804.Accordingly, disposable housing assembly 804 may include sealingassembly 970. Sealing assembly 970 may include, for example, anelastomeric member that may provide a compressible rubber or plasticlayer between reusable housing assembly 802 and disposable housingassembly 804 when engaged, thus preventing inadvertent disengagement andpenetration by outside fluids. For example, sealing assembly 970 may bea watertight seal assembly and, thus, enable a user to wear infusionpump assembly 800 while swimming, bathing or exercising.

In a fashion similar to, e.g., disposable housing assembly 114,disposable housing assembly 802 may, in some embodiments, be configuredto have reservoir 908 filled a plurality of times. However, in someembodiments, disposable housing assembly 114 may be configured such thatreservoir 908 may not be refilled. Referring also to FIGS. 57-64, filladapter 1000 may be configured to be coupled to disposable housingassembly 804 for refilling reservoir 908 using a syringe (not shown).Fill adapter 1000 may include locking tabs 1002, 1004, 1006, 1008 thatmay be configured to engage radial tabs 934, 936, 938, 940 of disposablehousing assembly 804 in a manner generally similar to tabs 942, 944,946, 948 of locking ring assembly 806. Accordingly, fill adapter 1000may be releasably engaged with disposable housing assembly 804 byaligning fill adapter 1000 with disposable housing assembly 804 androtating fill adapter 1000 and disposable housing assembly 804 relativeto one another to releasably engage locking tabs 1002, 1004, 1006, 1008with radial tabs 934, 936, 938, 940.

Fill adapter 1000 may further include filling aid 1010, which mayinclude guide passage 1012, e.g., which may be configured to guide aneedle of a syringe (not shown) to a septum of disposable housingassembly 804 to allow reservoir 908 of disposable housing assembly 804to be filled by the syringe. In some embodiments, guide passage 1012 maybe an angled bevel or other gradual angled bevel to further guide asyringe to a septum. Fill adapter 1000 may facilitate filling reservoir908 by providing a relatively large insertion area, e.g., at the distalopening of guide passage 1012. Guide passage 1012 may generally taper toa smaller proximal opening that may be properly aligned with the septumof disposable housing assembly 804, when fill adapter 1000 is engagedwith disposable housing assembly 804. Accordingly, fill adapter 1000 mayreduce the dexterity and aim necessary to properly insert a needlethrough the septum of disposable housing assembly 804 for the purpose offilling reservoir 908.

As discussed above, disposable housing assembly 804 may configured tofacilitate controlling the quantity of infusible fluid delivered toreservoir 908 during filling. For example, membrane assembly 902 ofdisposable housing assembly 804 may include ribs 964, 966, 968 that maybe depressed and at least partially displaced into reservoir 908,thereby reducing the volume of reservoir 908. Accordingly, wheninfusible fluid is delivered to reservoir 908, the volume of fluid thatmay be accommodated by reservoir 908 may be correspondingly reduced.Ribs 964, 966, 968 may be accessible via openings 958, 960, 962 in topportion 904 of disposable housing assembly 804.

Fill adapter 1000 may include one or more button assemblies (e.g.,button assemblies 1014, 1016, 1018) corresponding to ribs 964, 966, 968.That is, when fill adapter 1000 is releasably engaged with disposablehousing assembly 804, buttons 1014, 1016, 1018 may be aligned with ribs964, 966, 968. Button assemblies 1014, 1016, 1018 may be, for example,cantilever members capable of being depressed. When fill adapter 1000 isreleasably engaged with disposable housing assembly 804, one or more ofbutton assemblies 1014, 1016, 1018 may be depressed, and maycorrespondingly displace a respective one of ribs 964, 966, 698 intoreservoir 908, causing an attendant reduction in the volume of reservoir908.

For example, assume for illustrative purposes that reservoir 908 has amaximum capacity of 3.00 mL. Further, assume that button assembly 1014is configured to displace rib 964 into disposable housing assembly 804,resulting in a 0.5 mL reduction in the 3.00 mL capacity of disposablehousing assembly 804. Further, assume that button assembly 1016 isconfigured to displace rib 966 into disposable housing assembly 804,also resulting in a 0.5 mL reduction in the 3.00 mL capacity ofdisposable housing assembly 804. Further, assume that button assembly1018 is configured to displace slot assembly 968 into disposable housingassembly 804, also resulting in a 0.5 mL reduction in the 3.00 mLcapacity of disposable housing assembly 804. Therefore, if the userwishes to fill reservoir 908 within disposable housing assembly 804 with2.00 mL of infusible fluid, in some embodiments, the user may first fillthe reservoir to the 3.00 mL capacity and then depresses buttonassemblies 1016 and 1014 (resulting in the displacement of rib 966 intodisposable housing assembly 804), effectively reducing the 3.00 mLcapacity of reservoir 908 within disposable housing assembly 804 to 2.00mL. In some embodiments, the user may first depress a respective numberof button assemblies, effectively reducing the capacity of reservoir908, and then fill reservoir 908. Although a particular number of buttonassemblies are shown, representing the exemplary embodiment, in otherembodiments, the number of button assemblies may vary from a minimum of1 to as many as is desired. Additionally, although for descriptivepurposes, and in the exemplary embodiment, each button assembly maydisplace 0.5 mL, in other embodiments, the volume of displacement perbutton may vary. Additionally, the reservoir may be, in variousembodiments, include a larger or smaller volume than described in theexemplary embodiment.

According to the above-described configuration, the button assemblies(e.g., button assemblies 1014, 1016, 108) may employed, at least inpart, to control the fill volume of reservoir 908. By not depressing anyof the button assemblies, the greatest fill volume of reservoir 908 maybe achieved. Depressing one button assembly (e.g., button assembly 1014)may allow the second greatest fill volume to be achieved. Depressing twobutton assemblies (e.g., button assemblies 1014, 1016) may achieve thethird greatest fill volume. Depressing all three button assemblies(e.g., button assemblies 1014, 1016, 1018) may allow the smallest fillvolume to be achieve.

Further, in an embodiment button assemblies 1014, 1016, 1018 may beutilized, at least in part, to facilitate filling of reservoir 908. Forexample, once a filling needle (e.g., which may be fluidly coupled to avial of infusible fluid) has been inserted into reservoir 908, buttonassemblies 1014, 1016, 1018 may be depressed to pump at least a portionof any air that may be contained within reservoir into the vial ofinfusible fluid. Button assemblies 1014, 1016, 1018 may subsequently bereleased to allow infusible fluid to flow from the vial into reservoir908. Once reservoir 908 has been filled with the infusible fluid, one ormore button assemblies (e.g., one or more of button assemblies 1014,1016, 1018) may be depressed, thereby squeezing at least a portion ofthe infusible fluid from reservoir 908 (e.g., via a needle used to fillreservoir 908 and back into the vial of infusible fluid). As discussedabove, the volume of infusible fluid contained within reservoir 908 maybe controlled, e.g., depending upon how many button assemblies aredepressed (e.g., which may control how much infusible fluid is squeezedback into the vial of infusible fluid).

With particular reference to FIGS. 62-64, filling aid 1010 may bepivotally coupled to fill adapter base plate 1020. For example, fillingaid 1010 may include pivot members 1022, 1024 that may be configured tobe received in pivot supports 1026, 1028, thereby allowing filling aidto pivot between an open position (e.g., as shown in FIGS. 57-61) and aclosed position (e.g., as shown in FIGS. 63-64). The closed position maybe suitable, e.g., for packaging fill adapter 1000, storage of filladapter 1000, or the like. In order to ensure that filling aid 1010 isproperly oriented for filling reservoir 908, fill adapter 1000 mayinclude support member 1030. To properly orient filling aid 1010, a usermay pivot filling aid 1010 to a fully open position, wherein filling aid1010 may contact support member 1030.

According to an alternative embodiment, and referring also to FIG. 65,fill adapter 1050 may be configured to releasably engage disposablehousing assembly 804 via a plurality of locking tabs (e.g., locking tabs1052, 1054). Additionally, fill adapter 1050 may include a plurality ofbutton assemblies (e.g., button assemblies 1056, 1058, 1060) that mayinteract with ribs 964, 966, 968 of disposable housing assembly 804 toadjust a fill volume of reservoir 908. Fill adapter 1050 may furtherinclude filling aid 1062, having guide passage 1064 configured to aligna needle of a syringe with the septum of disposable housing 804, e.g.,for accessing reservoir 908 for the purpose of filling reservoir 908with an infusible fluid. Filling aid 1062 may be connected to base plate1066, e.g., as an integral component therewith, by gluing, heat sealing,compression fit, or the like.

Referring also to FIGS. 66-74, vial fill adapter 1100 may be configuredto facilitate filling reservoir 908 of disposable housing assembly 804directly from a vial. Similar to fill adapter 1000, vial fill adapter1100 may include locking tabs 1102, 1104, 1106, 1108 that may beconfigured to engage radial tabs 934, 936, 938, 940 of disposablehousing assembly in a manner generally similar to tabs 942, 944, 946,948 of locking ring assembly 806. Accordingly, vial fill adapter 1100may be releasably engaged with disposable housing assembly 804 byaligning vial fill adapter 1100 with disposable housing assembly 804 androtating vial fill adapter 1100 and disposable housing assembly 804relative to one another to releasably engage locking tabs 1102, 1104,1106, 1108 with radial tabs 934, 936, 938, 940.

As discussed above, disposable housing assembly 804 may be configured tofacilitate controlling the quantity of infusible fluid delivered toreservoir 908 during filling. For example, membrane assembly 902 ofdisposable housing assembly 804 may include ribs 964, 966, 968 that maybe depressed and at least partially displaced into reservoir 908,thereby reducing the volume of reservoir 908. Accordingly, wheninfusible fluid is delivered to reservoir 908, the volume of fluid thatmay be accommodated by reservoir 908 may be correspondingly reduced.Ribs 964, 966, 968 may be accessible via openings 958, 960, 962 in topportion 904 of disposable housing assembly 804.

Vial fill adapter 1100 may include one or more button assemblies (e.g.,button assemblies 1110, 1112, 1114) corresponding to ribs 964, 966, 968(e.g., shown in FIG. 52A). That is, when vial fill adapter 1100 isreleasably engaged with disposable housing assembly 804, buttons 1110,1112, 1114 may be aligned with ribs 964, 966, 968. Button assemblies1110, 1112, 1114 may be, for example, cantilever members capable ofbeing depressed. When vial fill adapter 1100 is releasably engaged withdisposable housing assembly 804, one or more of button assemblies 1110,1112, 1114 may be depressed, and may correspondingly displace arespective one of ribs 964, 966, 698 into reservoir 908, therebyreducing the volume of reservoir 908.

For example, assume for illustrative purposes that reservoir 908 has amaximum capacity of 3.00 mL. Further, assume that button assembly 1110is configured to displace rib 964 into disposable housing assembly 804,resulting in a 0.5 mL reduction in the 3.00 mL capacity of disposablehousing assembly 804. Further, assume that button assembly 1112 isconfigured to displace rib 966 into disposable housing assembly 804,also resulting in a 0.5 mL reduction in the 3.00 mL capacity ofdisposable housing assembly 804. Further, assume that button assembly1114 is configured to displace rib 968 into disposable housing assembly804, also resulting in a 0.50 mL reduction in the 3.00 mL capacity ofdisposable housing assembly 804. Therefore, if the user wishes to fillreservoir 908 within disposable housing assembly 804 with 2.00 mL ofinfusible fluid, the user may depress button assemblies 1112 and 1114(resulting in the displacement of ribs 966 and 968 into disposablehousing assembly 804), effectively reducing the 3.00 mL capacity ofreservoir 908 within disposable housing assembly 804 to 2.0 mL.

Vial fill adapter 1100 may further include vial filling aid assembly1116 that may be configured to fluidly couple a vial of infusible fluidto reservoir 908 of disposable housing assembly 804 via a septum. Withparticular reference to FIG. 71, vial filling aid assembly may includedouble ended needle assembly 1118. Double ended needle assembly 1118 mayinclude first needle end 1120 configured to penetrate the septum of avial (not shown) and second needle end 1122 configured to penetrate theseptum of disposable housing assembly 804. As such, the vial andreservoir 908 may be fluidly coupled allowing infusible fluid to betransferred from the vial to reservoir 908. Double ended needle assembly1118 may include vial engagement portion 1124 adjacent first end 1120.Vial engagement arms 1124, 1126 may be configured to releasably engage,e.g., a vial cap, to assist in maintaining the fluid connection betweendouble ended needle assembly 1118 and the vial. Additionally, doubleended needle assembly 1118 may include body 1128 that may be slidablyreceived in opening 1130 of vial filling aid body 1132. Vial filling aidbody 1132 may include stabilizer arms 1134, 1136, e.g., which may beconfigured to stabilize the vial during filling of disposable housingassembly 804. In one embodiment, the vial may be engaged with doubleended needle assembly 1118 e.g., such that first end 1120 may penetratethe septum of the vial and the cap of the vial may be engaged byengagement arms 1124, 1126. Body 1128 may be slidably inserted intoopening 1130 such that second end 1122 of double ended needle assembly1118 may penetrate the septum of disposable body assembly 804.

Similar to fill adapter 1000, vial filling aid assembly 1116 may beconfigured to be pivotally coupled to vial fill adapter base plate 1138.For example, vial filling aid 1116 may include pivot members 1140, 1142that may be configured to be received in pivot supports 1144, 1146(e.g., shown in FIG. 71), thereby allowing vial filling aid 1116 topivot between an open position (e.g., as shown in FIGS. 66-70) and aclosed position (e.g., as shown in FIGS. 72-74). The closed position maybe suitable, e.g., for packaging vial fill adapter 1100, storage of vialfill adapter 1100, or the like. In order to ensure that vial filling aid1116 is properly oriented for filling reservoir 908, vial fill adapter1100 may include support member 1148. To properly orient vial fillingaid 1116, a user may pivot vial filling aid 1116 to a fully openposition, wherein vial filling aid 1116 may contact support member 1148.Additionally, vial fill adapter base plate 1138 may include one or morelocking features (e.g., locking tabs 1150, 1152) that may engage vialfiling aid 1116, and may maintain vial filling aid 1116 in the closedposition. Vial fill adapter base plate 1138 may also include features(e.g., tabs 1154, 1156) that may be configured to assist in retainingdouble ended needle assembly 1118, e.g., by preventing slidableseparation of double ended needle assembly 1118 from vial filling aidbody 1132.

As shown in FIGS. 72-74, filling aid assembly 1116 is in a closedposition. In this configuration, support member 1148 may additionallyfunction as a needle guard. When removing filling aid assembly 1116 fromdisposable housing assembly 804, support member 1148 may function tosafely allow a user to squeeze the ends and rotate filling aid assembly1116 for removal. As shown in FIG. 70, in the open position, supportmember 1148 may function as a stop to maintain proper orientation.

Referring again to FIGS. 57-73, the exemplary embodiments of the filladapter include a grip feature (e.g., 1166 in FIG. 72). Grip feature1166 may provide a grip interface for removal of the fill adapter fromdisposable housing assembly 804. Although shown in one configuration inthese figures, in other embodiments, the configuration may vary. Instill other embodiments, a grip feature may not be included.

According to one embodiment, fill adapter base plate 1020 and vial filladapter base plate 1138 may be interchangeable components. Accordingly,a single base plate (e.g., either fill adapter base plate 1020 or vialfill adapter base plate 1138 may be used with either filling aid 1010 orvial filling aid 1116. Accordingly, the number of distinct componentsthat are required for both filling adapters may be reduced, and a usermay have the ability to select the filling adapter that may be the mostsuitable for a given filling scenario.

The various embodiments of the fill adapters may provide many safelybenefits, including but not limited to: providing a system for fillingthe reservoir without handling a needle; protecting the reservoir fromunintentional contact with the needle, i.e., destruction of theintegrity of the reservoir through unintentional puncture; designed tobe ambidextrous; in some embodiments, may provide a system formaintaining air in the reservoir.

As discussed above, reusable housing assembly 802 may include battery832, e.g., which may include a rechargeable battery. Referring also toFIGS. 75-80, battery charger 1200 may be configured to recharge battery832. Battery charger 1200 may include housing 1202 having top plate1204. Top plate 1204 may include one or more electrical contacts 1206,generally, configured to be electrically coupled to electrical contacts834 of reusable housing assembly 802. Electrical contacts 1206 mayinclude, but are not limited to, electrical contact pads, spring biasedelectrical contact members, or the like. Additionally, top plate 1204may include alignment tabs 1208, 1210, which may be configured to matewith openings 836, 838 in base plate 818 of reusable housing assembly802 (e.g., as shown in FIG. 35C). The cooperation of alignment tabs1208, 1210 and openings 836, 838 may ensure that reusable housingassembly 802 is aligned with battery charger 1200 such that electricalcontacts 1206 of battery charger 1200 may electrically couple withelectrical contacts 834 of reusable housing assembly 802.

With reference also to FIGS. 77 and 78, battery charger 1200 may beconfigured to releasably engage reusable housing assembly 802. Forexample, in a similar manner as disposable housing assembly 804, batterycharger 1200 may include one or more locking tabs (e.g., locking tabs1212, 1214 shown in FIG. 76). The locking tabs (e.g., locking tabs 1212,1214) may be engaged by tabs 942, 944, 946, 948 of locking ring assembly806. As such, reusable housing assembly 802 may be aligned with batterycharger 1200 (via alignment tabs 1208, 1210) with locking ring 806 in afirst, unlocked position, as shown in FIG. 77. Locking ring 806 may berotated relative to battery charger 1200 in the direction of arrow 1216to releasably engage tabs 942, 944, 946, 948 of locking ring 806 withthe locking tabs (e.g., locking tabs 1212, 1214) of battery charger1200, as shown in FIG. 78.

In an embodiment, battery charger 1200 may include recessed region 1218,e.g., which may, in the exemplary embodiments, provide clearance toaccommodate reusable housing assembly 802 pumping and valvingcomponents. Referring also to FIGS. 79 & 80, battery charger 1200 mayprovide electrical current to electrical contacts 1206 (and thereby toreusable housing assembly 802 via electrical contacts 834) forrecharging battery 832 of reusable housing assembly 802. In someembodiments, when a signal indicative of a fully engaged reusablehousing is not provided, current may not be provided to electricalcontacts 1206. According to such an embodiment, the risk associated withan electrical short circuit (e.g., resulting from foreign objectscontacting electrical contacts 1206) and damage to reusable housingassembly 802 (e.g., resulting from improper initial alignment betweenelectrical contacts 1206 and electrical contacts 834) may be reduced.Additionally, battery charger 1200 may not unnecessarily draw currentwhen battery charger is not charging reusable housing assembly 802.

Still referring to FIGS. 79 and 80, battery charger 1200 may include alower housing portion 1224 and top plate 1204. Printed circuit board1222 (e.g., which may include electrical contacts 1206) may be disposedwithin a cavity included between top plate 1204 and lower housingportion 1224.

Referring also to FIGS. 81-89, various embodiments of batterycharger/docking stations are shown. FIGS. 81 and 82 depicts desktopcharger 1250 including recess 1252 configured to mate with and rechargea reusable housing assembly (e.g., reusable housing assembly 802). Thereusable housing assembly may rest in recess 1252 and or may bereleasably engaged in recess 1252, in a similar manner as discussedabove. Additionally, desktop charger 1250 may include recess 1254configured to mate with a remote control assembly (e.g., remote controlassembly 300). Recess 1254 may include a USB plug 1256, e.g., which maybe configured to couple with the remote control assembly when the remotecontrol assembly is disposed within recess 1254. USB plug 1256 may allowfor data transfer to/from the remote control assembly, as well ascharging of remote control assembly. Desktop charger 1250 may alsoinclude USB port 1258 (e.g., which may include a mini-USB port),allowing desktop charger to receive power (e.g., for charging thereusable housing assembly and/or the remote control assembly).Additionally/alternatively USB port 1258 may be configured for datatransfer to/from remote control assembly and/or reusable housingassembly, e.g., by connection to a computer (not shown).

Referring to FIGS. 83A-83B, similar to the previous embodiment, desktopcharger 1260 may include recess 1262 for mating with a reusable housingassembly (e.g., reusable housing assembly 1264). Desktop charger mayalso include recess 1266 configured to receive a remote control assembly(e.g., remote control assembly 1268). One or more of recess 1262, 1266may include electrical and/or data connections configure to chargeand/or transfer data to/from reusable housing assembly 1262 and/orremote control assembly 1268, respectively.

Referring to FIGS. 84A-84B, another embodiment of a desktop charger isshown. Similar to desktop charger 1260, desktop charger 1270 may includerecesses (not shown) for respectively mating with reusable housingassembly 1272 and remote control assembly 1274. As shown, desktopcharger 1270 may hold reusable housing assembly 1272 and remote controlassembly 1274 in a side-by-side configuration. Desktop charger 1270 mayinclude various electrical and data connection configured to chargeand/or transfer data to/from reusable housing assembly 1272 and/orremote control assembly 1274, as described in various embodiments above.

Referring to FIG. 85A-85D, collapsible charger 1280 may include recess1282 for receiving reusable housing assembly 1284 and remote controlassembly 1286. Collapsible charger 1280 may include various electricaland data connection configured to charge and/or transfer data to/fromreusable housing assembly 1284 and/or remote control assembly 1286, asdescribed in various embodiments above. Additionally, as shown in FIGS.85B-85D, collapsible charger 1280 may include pivotable cover 1288.Pivotable cover 1288 may be configured to pivot between an open position(e.g., as shown in FIG. 85B), in which reusable housing assembly 1284and remote control assembly 1286 may be docked in collapsible charger1280, and a closed position (e.g., as shown in FIG. 85D), in whichrecess 1282 may be covered by pivotable cover 1288. In the closedposition, recess 1282, as well as any electrical and/or data connectionsdisposed therein, may be protected from damage.

Referring to FIG. 86, wall charger 1290 may include recess 1292configured to receive reusable housing assembly 1294. Additionally, wallcharger 1290 may include recess 1296 configured to receive remotecontrol assembly 1298. Reusable housing assembly 1294 and remote controlassembly 1298 may be positioned in a stacked configuration, e.g.,thereby providing a relatively slim profile. A rear portion of wallcharger 1290 may include an electrical plug, configured to allow wallcharger to be plugged into an electrical receptacle. As such, wallcharger 1290, while plugged into the electrical receptacle, may achievea wall mounted configuration. Additionally, while plugged into theelectrical receptacle, wall charger 1290 may be provided with power forcharging reusable housing assembly 1294 and/or remote control assembly1298.

Referring to FIG. 87, wall charger 1300 may include recess 1302configured to receive remote control assembly 1304. Additionally, wallcharger may include a recess (not shown) configured to receive reusablehousing assembly 1306. Wall charger 1300 may be configured to positionremote control assembly 1304 and reusable housing assembly 1306 in aback-to-back configuration, which may provide a relatively thin profile.Additionally, wall charger 1300 may include an electrical plug 1308configured to be plugged into an electrical receptacle. Electrical plug1308 may include a stowable configuration, in which electrical plug 1308may be pivotable between a deployed position (e.g., as shown), and astowed position. In the deployed position, electrical plug 1308 may beoriented to be plugged into an electrical receptacle. In the stowedposition electrical plug 1308 may be disposed within recess 1310, whichmay protect electrical plug 1308 from damage and/or from damaging otheritems.

Referring to FIG. 88, charger 1320 may include recess 1322 configured toreceive reusable housing assembly 1324. Charger 1320 may additionallyinclude a recess (not shown) configured to receive remote controlassembly 1326. Charger 1320 may additionally include cover 1328. Cover1328 may be configured to pivot between an open position (as shown) anda closed position. When cover 1328 is in the open position, reusablehousing assembly 1324 and remote control assembly 1326 may be accessible(e.g., allowing a user to remove/install reusable housing assembly 1324and/or remote control assembly 1326 from/into charger 1320. When cover1324 is in the closed position, cover 1328 and charger body 1330 maysubstantially enclose reusable housing assembly 1324 and/or remotecontrol assembly 1326 and/or recess 1322 and the recess configured toreceive remote control assembly 1326, thereby providing damage and/ortamper protection for reusable housing assembly 1324, remote controlassembly 1326 and/or any electrical and/or data connection associatedwith charger 1320.

Referring to FIGS. 89A-89B, wall charger 1350 may include recess 1352configured to receive remote control assembly 1354. Wall charger 1350may also include recess 1356 configured to receive reusable housingassembly 1358. Wall charger 1350 may be configured to position remotecontrol assembly 1354 and reusable housing assembly 1358 in a generallyside-by-side configuration, thereby providing a relatively slim profile.Charger 1350 may additionally include electrical plug 1360, e.g., whichmay be configured to be plugged into an electrical receptacle.Electrical plug 1360 may include a stowable configuration, in whichelectrical plug 1360 may be pivotable between a deployed position (e.g.,as shown), and a stowed position. In the deployed position, electricalplug 1360 may be oriented to be plugged into an electrical receptacle.In the stowed position electrical plug 1360 may be disposed withinrecess 1362, which may protect electrical plug 1308 from damage and/orfrom damaging other items.

Infusion pump therapy may include volume and time specifications. Theamount of fluid dispensed together with the dispense timing may be twocritical factors of infusion pump therapy. As discussed in detail below,the infusion pump apparatus and systems described herein may provide fora method of dispensing fluid together with a device, system and methodfor measuring the amount of fluid dispensed. However, in a circumstancewhere the calibration and precision of the measurement devicecalibration is critical, there may be advantages to determining anycompromise in the precision of the measurement device as soon aspossible. Thus, there are advantages to off-board verification of volumeand pumping.

As discussed above, infusion pump assembly 100 may include volume sensorassembly 148 configured to monitor the amount of fluid infused byinfusion pump assembly 100. Further and as discussed above, infusionpump assembly 100 may be configured so that the volume measurementsproduced by volume sensor assembly 148 may be used to control, through afeedback loop, the amount of infusible fluid that is infused into theuser.

Referring also to FIGS. 90A-90C, there is shown one diagrammatic viewand two cross-sectional views of volume sensor assembly 148. Referringalso to FIGS. 91A-91I, there is shown various isometric and diagrammaticviews of volume sensor assembly 148 (which is shown to include upperhousing 1400). Referring also to FIGS. 92A-92I, there is shown variousisometric and diagrammatic views of volume sensor assembly 148 (withupper housing 1400 removed), exposing speaker assembly 622, referencemicrophone 626, and printed circuit board assembly 830. Referring alsoto FIGS. 93A-93I, there is shown various isometric and diagrammaticviews of volume sensor assembly 148 (with printed circuit board assembly830 removed), exposing port assembly 624. Referring also to FIGS.94A-94F, there is shown various isometric and diagrammaticcross-sectional views of volume sensor assembly 148 (with printedcircuit board assembly 830 removed), exposing port assembly 624.Referring also to FIG. 95, there are shown an exploded view of volumesensor assembly 148, exposing upper housing 1400, speaker assembly 622,reference microphone 626, seal assembly 1404, lower housing 1402, portassembly 624, spring diaphragm 628, and retaining ring assembly 1406.

The following discussion concerns the design and operation of volumesensor assembly 148 (which is shown in a simplified form in FIG. 96).For the following discussion, the following nomenclature may be used:

Symbols P Pressure p Pressure Perturbation V Volume v VolumePerturbation γ Specific Heat Ratio R Gas Constant ρ Density Z Impedancef Flow friction A Cross sectional Area L Length ω Frequency ξ Dampingratio α Volume Ratio Subscripts 0 Speaker Volume 1 Reference Volume 2Variable Volume k Speaker r Resonant Port z Zero p Pole

Derivation of the Equations for Volume Sensor Assembly 148:

Modeling the Acoustic Volumes

The pressure and volume of an ideal adiabatic gas may be related by:PV ^(γ) =K  [EQ#1]where K is a constant defined by the initial conditions of the system.

EQ#1 may be written in terms of a mean pressure, P, and volume, V, and asmall time-dependent perturbation on top of those pressures, p(t), v(t)as follows:(P+p(t))(V+v(t))^(γ) =K  [EQ#2]

Differentiating this equation may result in:{dot over (p)}(t)(V+v(t))^(γ)+γ(V+v(t))^(γ−1)(P+p(t)){dot over(v)}(t)=0  [EQ#3]which may simplify to:

$\begin{matrix}{{{\overset{.}{p}(t)} + {\gamma\;\frac{P + {p(t)}}{V + {v(t)}}{\overset{.}{v}(t)}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 4} \right\rbrack\end{matrix}$

If the acoustic pressure levels are much less than the ambient pressure,the equation may be further simplified to:

$\begin{matrix}{{{\overset{.}{p}(t)} + {\frac{\gamma\; P}{V}{\overset{.}{v}(t)}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 5} \right\rbrack\end{matrix}$

How good is this assumption? Using the adiabatic relation it may beshown that:

$\begin{matrix}{\frac{P}{V} = {\left( \frac{P + {p(t)}}{V + {v(t)}} \right)\left( \frac{P + {p(t)}}{P} \right)^{- \frac{\gamma + 1}{\gamma}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 6} \right\rbrack\end{matrix}$

Accordingly, the error in the assumption would be:

$\begin{matrix}{{error} = {1 - \left( \frac{P + {p(t)}}{P} \right)^{- \frac{\gamma + 1}{\gamma}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 7} \right\rbrack\end{matrix}$

A very loud acoustic signal (120 dB) may correspond to pressure sinewave with amplitude of roughly 20 Pascal. Assuming air at atmosphericconditions (γ=1.4, P=101325 Pa), the resulting error is 0.03%. Theconversion from dB to Pa is as follows:

$\begin{matrix}{{\lambda = {{20\;{\log_{10}\left( \frac{p_{{rm}\; s}}{p_{ref}} \right)}\mspace{20mu}{or}\mspace{20mu} p_{{rm}\; s}} = {p_{ref}10^{\frac{\lambda}{20}}}}}{{{where}\mspace{20mu} p_{ref}} = {{20 \cdot \mu}\; P\;{a.}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 8} \right\rbrack\end{matrix}$

Applying the ideal gas law, P=ρRT, and substituting in for pressure mayresult in the following:

$\begin{matrix}{{{\overset{.}{p}(t)} + {\frac{\gamma\;{RT}\;\rho}{V}{\overset{.}{v}(t)}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 9} \right\rbrack\end{matrix}$

EQ#9 may be written in terms of the speed of sound, a=√{square root over(γRT)} as follows:

$\begin{matrix}{{{\overset{.}{p}(t)} + {\frac{\rho\; a^{2}}{V}{\overset{.}{v}(t)}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 10} \right\rbrack\end{matrix}$

Acoustic impedance for a volume may be defined as follows:

$\begin{matrix}{Z_{v} = {\frac{p(t)}{\overset{.}{v}(t)} = \frac{1}{\left( \frac{V}{\rho\; a^{2}} \right)s}}} & \left\lbrack {{EQ}\#\mspace{14mu} 11} \right\rbrack\end{matrix}$

Modeling the Acoustic Port

The acoustic port may be modeled assuming that all of the fluid in theport essentially moves as a rigid cylinder reciprocating in the axialdirection. All of the fluid in the channel is assumed to travel at thesame velocity, the channel is assumed to be of constant cross section,and the “end effects” resulting from the fluid entering and leaving thechannel are neglected.

If we assume laminar flow friction of the form Δp=fρ{dot over (v)}, thefriction force acting on the mass of fluid in the channel may be writtenas follows:F=fρA ² {dot over (x)}  [EQ#12]

A second order differential equation may then be written for thedynamics of the fluid in the channel:ρLA{umlaut over (x)}=ΔpA−fρA ² {dot over (x)}  [EQ#13]

or, in terms of volume flow rate:

$\begin{matrix}{\overset{¨}{v} = {{{- \frac{f\; A}{L}}\overset{.}{v}} + {\Delta\; p\;\frac{A}{\rho\; L}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 14} \right\rbrack\end{matrix}$

The acoustic impedance of the channel may then be written as follows:

$\begin{matrix}{Z_{p} = {\frac{\Delta\; p}{\overset{.}{v}} = {\frac{\rho\; L}{A}\left( {s + \frac{fA}{L}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 15} \right\rbrack\end{matrix}$

System Transfer Functions

Using the volume and port dynamics defined above, volume sensor assembly148 may be described by the following system of equations: (k=speaker,r=resonator)

$\begin{matrix}{{{\overset{.}{p}}_{0} - {\frac{\rho\; a^{2}}{V_{0}}{\overset{.}{v}}_{k}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 16} \right\rbrack \\{{{\overset{.}{p}}_{1} + {\frac{\rho\; a^{2}}{V_{1}}\left( {{\overset{.}{v}}_{k} - {\overset{.}{v}}_{r}} \right)}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 17} \right\rbrack \\{{{\overset{.}{p}}_{2} + {\frac{\rho\; a^{2}}{V_{2}}{\overset{.}{v}}_{r}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 18} \right\rbrack \\{{\overset{¨}{v}}_{r} = {{{- \frac{fA}{L}}{\overset{.}{v}}_{r}} + {\frac{A}{\rho\; L}\left( {p_{2} - p_{1}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 19} \right\rbrack\end{matrix}$

One equation may be eliminated if p₀ is treated as the inputsubstituting in

${\overset{.}{v}}_{k} = {\frac{V_{0}}{\rho\; a^{2}}{{\overset{.}{p}}_{0}.}}$

$\begin{matrix}{{{\overset{.}{p}}_{1} + {\frac{V_{0}}{V_{1}}{\overset{.}{p}}_{0}} - {\frac{\rho\; a^{2}}{V_{1}}{\overset{.}{v}}_{r}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 20} \right\rbrack \\{{{\overset{.}{p}}_{2} + {\frac{\rho\; a^{2}}{V_{2}}{\overset{.}{v}}_{r}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 21} \right\rbrack \\{{\overset{¨}{v}}_{r} = {{{- \frac{fA}{L}}{\overset{.}{v}}_{r}} + {\frac{A}{\rho\; L}p_{2}} - {\frac{A}{\rho\; L}p_{1}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 22} \right\rbrack\end{matrix}$

Cross System Transfer Function

The relationship between the speaker volume and the variable volume maybe referred to as the Cross System transfer function. This transferfunction may be derived from the above equations and is as follows:

$\begin{matrix}{{\frac{p_{2}}{p_{0}} = {{- \frac{V_{0}}{V_{1}}}\frac{\omega_{n}^{2}}{s^{2} + {2{\zeta\omega}_{n}s} + {\alpha\omega}_{n}^{2}}}}{where}} & \left\lbrack {{EQ}\#\mspace{14mu} 23} \right\rbrack \\{{\omega_{n}^{2} = {\frac{a^{2}A}{L}\frac{1}{V_{2}}}},{\zeta = {{\frac{fA}{2L\;\omega_{n}}\mspace{14mu}{and}\mspace{14mu}\alpha} = \left( {1 + \frac{V_{2}}{V_{1}}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 24} \right\rbrack\end{matrix}$

Referring also to FIG. 97, a bode plot of EQ#23 is shown.

The difficulty of this relationship is that the complex poles depend onboth the variable volume, V₂, and the reference volume, V₁. Any changein the mean position of the speaker may result in an error in theestimated volume.

Cross Port Transfer Function

The relationship between the two volumes on each side of the acousticport may be referred to as the Cross Port transfer function. Thisrelationship is as follows:

$\begin{matrix}{\frac{p_{2}}{p_{1}} = \frac{\omega_{n}^{2}}{s^{2} + {2\zeta\;\omega_{n}s} + \omega_{n}^{2}}} & \left\lbrack {{EQ}\#\mspace{14mu} 25} \right\rbrack\end{matrix}$

which is shown graphically in FIG. 98.

This relationship has the advantage that the poles are only dependent onthe variable volume and not on the reference volume. It does, however,have the difficulty that the resonant peak is actually due to theinversion of the zero in the response of the reference volume pressure.Accordingly, the pressure measurement in the reference chamber will havea low amplitude in the vicinity of the resonance, potentially increasingthe noise in the measurement.

Cross Speaker Transfer Function

The pressures may also be measured on each side of the speaker. This isreferred to as the cross speaker transfer function:

$\begin{matrix}{\frac{p_{1}}{p_{0}} = {{- \frac{V_{0}}{V_{1}}}\frac{s^{2} + {2{\zeta\omega}_{n}s} + \omega_{n}^{2}}{s^{2} + {2{\zeta\omega}_{n}s} + {\alpha\omega}_{n}^{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 26} \right\rbrack\end{matrix}$

which is shown graphically in FIG. 99.

This transfer function has a set of complex zeros in addition to the setof complex poles.

Looking at the limits of this transfer function: as s→0,

$\left. \frac{p_{1}}{p_{0}}\rightarrow{- \frac{V_{0}}{V_{1} + V_{2}}} \right.;$and as s→∞,

$\left. \frac{p_{1}}{p_{0}}\rightarrow{- {\frac{V_{0}}{V_{1}}.}} \right.$

Resonance Q Factor and Peak Response

The quality of the resonance is the ratio of the energy stored to thepower loss multiplied by the resonant frequency. For a pure second-ordersystem, the quality factor may be expressed as a function of the dampingratio:

$\begin{matrix}{Q = \frac{1}{2\zeta}} & \left\lbrack {{EQ}\#\mspace{14mu} 27} \right\rbrack\end{matrix}$

The ratio of the peak response to the low-frequency response may also bewritten as a function of the damping ratio:

$\begin{matrix}{{G}_{\omega_{d}} = \frac{1}{\zeta\sqrt{5 - {4\zeta}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 28} \right\rbrack\end{matrix}$

This may occur at the damped natural frequency:ω_(d)=ω_(n)√{square root over (1−ξ)}  [EQ#29]Volume Estimation

Volume Estimation using Cross-Port Phase

The variable volume (i.e., within volume sensor chamber 620) may also beestimated using the cross-port phase. The transfer function for thepressure ratio across the resonant port may be as follows:

$\begin{matrix}{\frac{p_{2}}{p_{1}} = \frac{\omega_{n}^{2}}{s^{2} + {bs} + \omega_{n}^{2}}} & \left\lbrack {{EQ}\#\mspace{14mu} 30} \right\rbrack\end{matrix}$

At the 90° phase point, ω=ω_(n); where

$\omega_{n}^{2} = {\frac{1}{V_{2}}\frac{a^{2}A}{L}}$

The resonant frequency may be found on the physical system using anumber of methods. A phase-lock loop may be employed to find the 90°phase point—this frequency may correspond to the natural frequency ofthe system. Alternatively, the resonant frequency may be calculatedusing the phase at any two frequencies:

The phase, φ, at any given frequency will satisfy the followingrelation:

$\begin{matrix}{{{\tan\;\phi} = \frac{b\;\omega}{\omega^{2} - \omega_{n}^{2}}}{{{where}\mspace{14mu} b} = {\frac{fA}{L}.}}} & \left\lbrack {{EQ}\#\mspace{14mu} 31} \right\rbrack\end{matrix}$

Solving for V₂ results in:

$\begin{matrix}{V_{2} = \frac{\frac{a^{2}A}{L}}{\omega^{2} - {f\;\omega\;\cot\;\phi}}} & \left\lbrack {{EQ}\#\mspace{14mu} 32} \right\rbrack\end{matrix}$

Accordingly, the ratio of the phases at two different frequencies ω₁ andω₂ can be used to compute the natural frequency of the system:

$\begin{matrix}{{\alpha\;\omega_{n}^{2}} = {\omega_{1}\omega_{2}\frac{\left( {{\omega_{1}\frac{\tan\;\phi_{1}}{\tan\;\phi_{2}}} - \omega_{2}} \right)}{\left( {{\omega_{2}\frac{\tan\;\phi_{1}}{\tan\;\phi_{2}}} - \omega_{1}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 33} \right\rbrack\end{matrix}$

For computational efficiency, the actual phase does not need to becalculated. All that is needed is the ratio of the real and imaginaryparts of the response (tan φ).

Re-writing EQ#33 in terms of the variable volume results in:

$\begin{matrix}{\frac{1}{V_{2}} = {\frac{1}{a^{2}}\frac{L}{A}\omega_{1}\omega_{2}\frac{\left( {{\omega_{1}\frac{\tan\;\phi_{1}}{\tan\;\phi_{2}}} - \omega_{2}} \right)}{\left( {{\omega_{2}\frac{\tan\;\phi_{1}}{\tan\;\phi_{2}}} - \omega_{1}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 34} \right\rbrack\end{matrix}$

Volume Estimation using Swept Sine

The resonant frequency of the system may be estimated using swept-sinesystem identification. In this method, the response of the system to asinusoidal pressure variation may be found at a number of differentfrequencies. This frequency response data may then used to estimate thesystem transfer function using linear regression.

The transfer function for the system may be expressed as a rationalfunction of s. The general case is expressed below for a transferfunction with an n^(th) order numerator and an m^(th) order denominator.N and D are the coefficients for the numerator and denominatorrespectively. The equation has been normalized such that the leadingcoefficient in the denominator is 1.

$\begin{matrix}{{{G(s)} = \frac{{N_{n}s^{n}} + {N_{n - 1}s^{n - 1}} + \ldots + N_{0}}{s^{m} + {D_{m - 1}s^{m - 1}} + {D_{m - 2}s^{m - 2}} + \ldots + D_{0}}}{or}} & \left\lbrack {{EQ}\#\mspace{14mu} 35} \right\rbrack \\{{G(s)} = \frac{\sum\limits_{k = 0}^{n}{N_{k}s^{k}}}{s^{m} + {\sum\limits_{k = 0}^{m - 1}{D_{k}s^{k}}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 36} \right\rbrack\end{matrix}$

This equation may be re-written as follows:

$\begin{matrix}{{Gs}^{m} = {{\sum\limits_{k = 0}^{n}{N_{k}s^{k}}} - {G{\sum\limits_{k = 0}^{m - 1}{D_{k}s^{k}}}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 37} \right\rbrack\end{matrix}$

Representing this summation in matrix notation resulting in thefollowing:

$\begin{matrix}{\begin{bmatrix}{G_{1}s_{1}^{m}} \\\vdots \\{G_{k}s_{k}^{m}}\end{bmatrix} = {\begin{bmatrix}s_{1}^{n} & \ldots & s_{1}^{0} & {{- G_{1}}s_{1}^{m - 1}} & \ldots & {{- G_{1}}s_{1}^{0}} \\\vdots & \; & \vdots & \vdots & \; & \vdots \\s_{k}^{n} & \ldots & s_{k}^{0} & {{- G_{k}}s_{k}^{m - 1}} & \ldots & {{- G_{k}}s_{k}^{0}}\end{bmatrix}\begin{bmatrix}N_{n} \\\vdots \\N_{0} \\D_{m - 1} \\\vdots \\D_{0}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 38} \right\rbrack\end{matrix}$

where k is the number of data points collected in the swept sine. Tosimplify the notation, this equation may be summarized using thevectors:y=Xc  [EQ#39]

where y is k by 1, x is k by (m+n−1) and c is (m+n−1) by 1. Thecoefficients may then be found using a least square approach. The errorfunction may be written as follows:e=y−Xc  [EQ#40]

The function to be minimized is the weighted square of the errorfunction; W is a k×k diagonal matrix.e ^(T) We=(y−Xc)^(T) W(y−Xc)  [EQ#41]e ^(T) We=y ^(T) Wy−(y ^(T) WXc)^(T) −y ^(T) WXc+c ^(T) x ^(T)WXc  [EQ#42]

As the center two terms are scalars, the transpose may be neglected.

$\begin{matrix}{{e^{T}{We}} = {{y^{T}{Wy}} - {2y^{T}{WXc}} + {c^{T}x^{T}{WXc}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 43} \right\rbrack \\{\frac{{\partial e^{T}}{We}}{\partial c} = {{{{- 2}X^{T}{Wy}} + {2X^{T}{WXc}}} = 0}} & \left\lbrack {{EQ}\#\mspace{14mu} 44} \right\rbrack \\{c = {\left( {X^{T}{WX}} \right)^{- 1}X^{T}{Wy}}} & \left\lbrack {{EQ}\#\mspace{14mu} 45} \right\rbrack\end{matrix}$

It may be necessary to use the complex transpose in all of these cases.This approach may result in complex coefficients, but the process may bemodified to ensure that all the coefficients are real. The least-squareminimization may be modified to give only real coefficients if the errorfunction is changed to bee ^(T) We=Re(y−Xc)^(T) WRe(y−Xc)+Im(y−Xc)^(T) WIm(y−Xc)  [EQ#46]

Accordingly, the coefficients may be found with the relation:c=(Re(X)^(T) WRe(X)+Im(X)^(T) WIm(X))⁻¹(Re(X)^(T) WRe(y)+Im(X)^(T)WIm(y))  [EQ#47]

Solution for a 2nd Order System

For a system with a 0^(th) order numerator and a second orderdenominator as shown in the transfer function:

$\begin{matrix}{{G(s)} = \frac{N_{0}}{s^{2} + {D_{1}s} + D_{0}}} & \left\lbrack {{EQ}\#\mspace{14mu} 48} \right\rbrack\end{matrix}$

The coefficients in this transfer function may be found based on theexpression found in the previous section:

$\begin{matrix}{{c = {\begin{pmatrix}{{{Re}(X)^{T}W\;{{Re}(X)}} +} \\{{Im}(X)^{T}W\;{{Im}(X)}}\end{pmatrix}^{- 1}\begin{pmatrix}{{{Re}(X)^{T}W\;{{Re}(y)}} +} \\{{Im}(X)^{T}W\;{{Im}(y)}}\end{pmatrix}}}{{where}\text{:}}} & \left\lbrack {{EQ}\#\mspace{14mu} 49} \right\rbrack \\{{y = \begin{bmatrix}{G_{1}s_{1}^{2}} \\\vdots \\{G_{k}s_{k}^{2}}\end{bmatrix}},{X = \begin{bmatrix}1 & {{- G_{1}}s_{1}} & {- G_{1}} \\\vdots & \vdots & \vdots \\1 & {{- G_{k}}s_{k}} & {- G_{k}}\end{bmatrix}},{{{and}\mspace{14mu} c} = \begin{bmatrix}N_{0} \\D_{1} \\D_{0}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 50} \right\rbrack\end{matrix}$

To simplify the algorithm, we may combine some of terms:c=D ⁻¹ b  [EQ#51]where:D=Re(X)^(T) WRe(X)+Im(X)^(T) WIm(X)  [EQ#52]b=Re(X)^(T) WRe(y)+Im(X)^(T) WIm(y)  [EQ#53]

To find an expression for D in terms of the complex response vector Gand the natural frequency s=jω, X may be split into its real andimaginary parts:

$\begin{matrix}{{{{Re}(X)} = \begin{bmatrix}1 & {\omega_{k}{{Im}\left( G_{1} \right)}} & {- {{Re}\left( G_{1} \right)}} \\\vdots & \vdots & \vdots \\1 & {\omega_{k}{{Im}\left( G_{k} \right)}} & {- {{Re}\left( G_{k} \right)}}\end{bmatrix}},{{{Im}(X)} = \begin{bmatrix}0 & {{- \omega_{k}}{{Re}\left( G_{1} \right)}} & {- {{Im}\left( G_{1} \right)}} \\\vdots & \vdots & \vdots \\0 & {{- \omega_{k}}{{Re}\left( G_{k} \right)}} & {- {{Im}\left( G_{k} \right)}}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 54} \right\rbrack\end{matrix}$

The real and imaginary portions of the expression for D above may thenbecome:

$\begin{matrix}{{{{Re}(X)}^{T}W\;{{Re}(X)}} = \left\lbrack \begin{matrix}{\sum\limits_{i = 1}^{k}w_{i}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}}}} \\{\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}^{2}\omega_{i}^{2}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}}}} \\{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}^{2}}}\end{matrix} \right\rbrack} & \left\lbrack {{EQ}\#\mspace{14mu} 55} \right\rbrack \\{{{{Im}(X)}^{T}W\;{{Im}(X)}} = \mspace{110mu}\begin{bmatrix}0 & 0 & 0 \\0 & {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}^{2}\omega_{i}^{2}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}}} \\0 & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}^{2}}}\end{bmatrix}} & \left\lbrack {{EQ}\#\mspace{14mu} 56} \right\rbrack\end{matrix}$

Combining these terms results in the final expression for the D matrix,which may contain only real values.

$\begin{matrix}{D = \left\lbrack \begin{matrix}{\sum\limits_{i = 1}^{k}w_{i}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}}}} \\{\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}}} & {\sum\limits_{i = 1}^{k}{{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}\omega_{i}^{2}}} & 0 \\{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}}}} & 0 & {\sum\limits_{i = 1}^{k}{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}}\end{matrix} \right\rbrack} & \left\lbrack {{EQ}\#\mspace{14mu} 57} \right\rbrack\end{matrix}$

The same approach may be taken to find an expression for the b vector interms of G and ω. The real and imaginary parts of y are as follows:

$\begin{matrix}{{{{Re}(y)} = \begin{bmatrix}{{- {{Re}\left( G_{1} \right)}}\omega_{1}^{2}} \\\vdots \\{{- {{Re}\left( G_{k} \right)}}\omega_{k}^{2}}\end{bmatrix}},{{{Im}(y)} = \begin{bmatrix}{{- {{Im}\left( G_{1} \right)}}\omega_{1}^{2}} \\\vdots \\{{- {{Im}\left( G_{k} \right)}}\omega_{k}^{2}}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 58} \right\rbrack\end{matrix}$

Combining the real and imaginary parts results in the expression for theb vector as follows:

$\begin{matrix}\begin{matrix}{b = {{{{Re}(X)}^{T}W\;{{Re}(y)}} + {{{Im}(X)}^{T}W\;{{Im}(y)}}}} \\{= \begin{bmatrix}{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}\omega_{i}^{2}}}} \\0 \\{\sum\limits_{i = 1}^{k}{{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}\omega_{i}^{2}}}\end{bmatrix}}\end{matrix} & \left\lbrack {{EQ}\#\mspace{14mu} 59} \right\rbrack\end{matrix}$

The next step is to invert the D matrix. The matrix is symmetric andpositive-definite so the number of computations needed to find theinverse will be reduced from the general 3×3 case. The generalexpression for a matrix inverse is:

$\begin{matrix}{D^{- 1} = {\frac{1}{\det(D)}{{adj}(D)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 60} \right\rbrack\end{matrix}$

If D is expressed as follows:

$\begin{matrix}{D = \begin{bmatrix}d_{11} & d_{12} & d_{13} \\d_{12} & d_{22} & 0 \\d_{13} & 0 & d_{33}\end{bmatrix}} & \left\lbrack {{EQ}\#\mspace{14mu} 61} \right\rbrack\end{matrix}$

then the adjugate matrix may be written as follows:

$\begin{matrix}\begin{matrix}{{{adj}(D)} = \begin{bmatrix}{\begin{matrix}d_{22} & 0 \\0 & d_{33}\end{matrix}} & {- {\begin{matrix}d_{12} & 0 \\d_{13} & d_{33}\end{matrix}}} & {\begin{matrix}d_{12} & d_{22} \\d_{13} & 0\end{matrix}} \\{- {\begin{matrix}d_{12} & d_{13} \\0 & d_{33}\end{matrix}}} & {\begin{matrix}d_{11} & d_{13} \\d_{13} & d_{33}\end{matrix}} & {- {\begin{matrix}d_{11} & d_{12} \\d_{13} & 0\end{matrix}}} \\{\begin{matrix}d_{12} & d_{13} \\d_{22} & 0\end{matrix}} & {- {\begin{matrix}d_{11} & d_{13} \\d_{12} & 0\end{matrix}}} & {\begin{matrix}d_{11} & d_{12} \\d_{12} & d_{22}\end{matrix}}\end{bmatrix}} \\{= \begin{bmatrix}a_{11} & a_{12} & a_{13} \\a_{12} & a_{22} & a_{23} \\a_{13} & a_{32} & a_{33}\end{bmatrix}}\end{matrix} & \left\lbrack {{EQ}\#\mspace{14mu} 62} \right\rbrack\end{matrix}$

Due to symmetry, only the upper diagonal matrix may need to becalculated.

The Determinant may then be computed in terms of the adjugate matrixvalues, taking advantage of the zero elements in the original array:det(D)=a ₁₂ d ₁₂ +a ₂₂ d ₂₂  [EQ#63]

Finally, the inverse of D may be written as follows:

$\begin{matrix}{D^{- 1} = {\frac{1}{\det(D)}{{adj}(D)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 64} \right\rbrack\end{matrix}$

Since we are trying to solve:

$\begin{matrix}{{c = {{D^{- 1}b} = {\frac{1}{\det(D)}{{adj}(D)}b}}}{{then}\text{:}}} & \left\lbrack {{EQ}\#\mspace{14mu} 65} \right\rbrack \\\begin{matrix}{c = {{\frac{1}{\det(D)}\begin{bmatrix}a_{11} & a_{12} & a_{13} \\a_{12} & a_{22} & a_{23} \\a_{13} & a_{32} & a_{33}\end{bmatrix}}\begin{bmatrix}b_{1} \\0 \\b_{3}\end{bmatrix}}} \\{= {\frac{1}{\det(D)}\begin{bmatrix}{{a_{11}b_{1}} + {a_{13}b_{3}}} \\{{a_{12}b_{1}} + {a_{23}b_{3}}} \\{{a_{13}b_{1}} + {a_{33}b_{3}}}\end{bmatrix}}}\end{matrix} & \left\lbrack {{EQ}\#\mspace{14mu} 66} \right\rbrack\end{matrix}$

The final step is to get a quantitative assessment of how well the datafits the model. Accordingly, the original expression for the error is asfollows:e ^(T) We=Re(y−Xc)^(T) WRe(y−Xc)+Im(y−Xc)^(T) WIm(y−Xc)  [EQ#67]

This may be expressed in terms of the D matrix and the b and c vectorsas follows:e ^(T) We=h−2c ^(T) b+c ^(T) Dc  [EQ#68]

where:

$\begin{matrix}{{{e^{T}{We}} = {h - {2c^{T}b} + {c^{T}{Dc}}}}{{where}\text{:}}} & \left\lbrack {{EQ}\#\mspace{14mu} 68} \right\rbrack \\{h = {{{{Re}\left( y^{T} \right)}W\;{{Re}(y)}} + {{{Im}\left( y^{T} \right)}W\;{{Im}(y)}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 69} \right\rbrack \\{h = {\sum\limits_{i = 1}^{k}{{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}\omega_{i}^{4}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 70} \right\rbrack\end{matrix}$

The model fit error may also be used to detect sensor failures.

Alternate Solution for a 2nd Order System

$\begin{matrix}{{{G(s)} = \frac{{N_{n}s^{n}} + {N_{n - 1}s^{n - 1}} + \ldots + N_{0}}{s^{m} + {D_{m - 1}s^{m - 1}} + {D_{m - 2}s^{m - 2}} + \ldots + D_{0}}}{or}} & \left\lbrack {{EQ}\#\mspace{14mu} 71} \right\rbrack \\{{G(s)} = \frac{\sum\limits_{k = 0}^{n}{N_{k}s^{k}}}{s^{m} + {\sum\limits_{k = 0}^{m - 1}{D_{k}s^{k}}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 72} \right\rbrack\end{matrix}$

This equation may be re-written as follows:

$\begin{matrix}{G = {{\sum\limits_{k = 0}^{n}{N_{k}s^{k - m}}} - {G{\sum\limits_{k = 0}^{m - 1}{D_{k}s^{k - m}}}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 73} \right\rbrack\end{matrix}$

Putting this summation into matrix notation results in the following:

$\begin{matrix}{\begin{bmatrix}G_{1} \\\vdots \\G_{k}\end{bmatrix} = {\begin{bmatrix}s_{1}^{n - m} & \ldots & s_{1}^{- m} & {{- G_{1}}s_{1}^{- 1}} & \ldots & {{- G_{1}}s_{1}^{- m}} \\\vdots & \; & \vdots & \vdots & \; & \vdots \\s_{k}^{n - m} & \ldots & s_{k}^{- m} & {{- G_{k}}s_{k}^{- 1}} & \ldots & {{- G_{k}}s_{k}^{- m}}\end{bmatrix}\begin{bmatrix}N_{n} \\\vdots \\N_{0} \\D_{m - 1} \\\vdots \\D_{0}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 74} \right\rbrack\end{matrix}$

For a system with a 0^(th) order numerator and a second orderdenominator as shown in the transfer function:

$\begin{matrix}{{G(s)} = \frac{N_{0}}{s^{2} + {D_{1}s} + D_{0}}} & \left\lbrack {{EQ}\#\mspace{14mu} 75} \right\rbrack\end{matrix}$

The coefficients in this transfer function may be found based on theexpression found in the previous section:c=(Re(X)^(T) WRe(X)+Im(X)^(T) WIm(X))⁻¹(Re(X)^(T) WRe(y)+Im(X)^(T)WIm(y))  [EQ#76]

where

$\begin{matrix}{{c = {\begin{pmatrix}{{{Re}(X)^{T}W\;{{Re}(X)}} +} \\{{Im}(X)^{T}W\;{{Im}(X)}}\end{pmatrix}^{- 1}\begin{pmatrix}{{{Re}(X)^{T}W\;{{Re}(y)}} +} \\{{Im}(X)^{T}W\;{{Im}(y)}}\end{pmatrix}}}{where}} & \left\lbrack {{EQ}\#\mspace{14mu} 76} \right\rbrack \\{{{y = \begin{bmatrix}G_{1} \\\vdots \\G_{k}\end{bmatrix}},{X = \begin{bmatrix}s_{1}^{- 2} & {{- G_{1}}s_{1}^{- 1}} & {{- G_{1}}s_{1}^{- 2}} \\\vdots & \vdots & \vdots \\S_{k}^{- 2} & {{- G_{k}}s_{k}^{- 1}} & {{- G_{k}}s_{k}^{- 2}}\end{bmatrix}},{and}}{c = \begin{bmatrix}N_{0} \\D_{1} \\D_{0}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 77} \right\rbrack\end{matrix}$

To simplify the algorithm, some terms may be combined:c=D ⁻¹ b  [EQ#78]where:D=Re(X)^(T) WRe(X)+Im(X)^(T) WIm(X)  [EQ#79]b=Re(X)^(T) WRe(y)+Im(X)^(T) WIm(y)  [EQ#80]

To find an expression for D in terms of the complex response vector Gand the natural frequency s=jω, split X may be split into its real andimaginary parts:

$\begin{matrix}{{{Re}(X)} = \begin{bmatrix}{- \omega_{1}^{- 2}} & {{- \omega_{1}^{- 1}}{{Im}\left( G_{1} \right)}} & {\omega_{1}^{- 2}{{Re}\left( G_{1} \right)}} \\\vdots & \vdots & \vdots \\{- \omega_{k}^{- 2}} & {{- \omega_{k}^{- 1}}{{Im}\left( G_{k} \right)}} & {\omega_{k}^{- 2}{{Re}\left( G_{k} \right)}}\end{bmatrix}} & \left\lbrack {{EQ}\#\mspace{14mu} 81} \right\rbrack \\{{{Im}(X)} = \begin{bmatrix}0 & {{- \omega_{1}^{- 1}}{{Re}\left( G_{1} \right)}} & {\omega_{1}^{- 2}{{Im}\left( G_{1} \right)}} \\\vdots & \vdots & \vdots \\0 & {{- \omega_{k}^{- 1}}{{Re}\left( G_{k} \right)}} & {\omega_{k}^{- 2}{{Im}\left( G_{k} \right)}}\end{bmatrix}} & \left\lbrack {{EQ}\#\mspace{14mu} 82} \right\rbrack\end{matrix}$

The real and imaginary portions of the expression for D above may thenbecome:

$\begin{matrix}{{{{Re}(X)}^{T}W\;{{Re}(X)}} = {\quad\begin{bmatrix}{\sum\limits_{i = 1}^{k}{w_{i}\omega_{i}^{- 4}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}^{- 3}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}\omega_{i}^{- 4}}}} \\{\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}^{- 3}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}^{2}\omega_{i}^{- 2}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}^{- 3}}}} \\{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}\omega_{i}^{- 4}}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}^{- 3}}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}^{2}\omega_{i}^{- 4}}}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 83} \right\rbrack \\{{{{Im}(X)}^{T}W\;{{Im}(X)}} = {\quad\begin{bmatrix}0 & 0 & 0 \\0 & {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}^{2}\omega_{i}^{- 2}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}^{- 3}}}} \\0 & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}^{- 3}}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}^{2}\omega_{i}^{- 4}}}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 84} \right\rbrack\end{matrix}$

Combining these terms results in the final expression for the D matrix,which may contain only real values.

$\begin{matrix}{\quad{D = \left\lbrack \begin{matrix}{\sum\limits_{i = 1}^{k}{w_{i}\omega_{i}^{- 4}}} & {\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}^{- 3}}} & {- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}\omega_{i}^{- 4}}}} \\{\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}\omega_{i}^{- 3}}} & {\sum\limits_{i = 1}^{k}{{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}\omega_{i}^{- 2}}} & {{- 2}{\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}^{- 3}}}} \\{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}\omega_{i}^{- 4}}}} & {{- 2}{\sum\limits_{i = 1}^{k}{w_{i}{{Im}\left( G_{i} \right)}{{Re}\left( G_{i} \right)}\omega_{i}^{- 3}}}} & {\sum\limits_{i = 1}^{k}{{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}\omega_{i}^{- 4}}}\end{matrix} \right\rbrack}} & \left\lbrack {{EQ}\#\mspace{14mu} 85} \right\rbrack\end{matrix}$

The same approach may be taken to find an expression for the b vector interms of G and ω. The real and imaginary parts of y areas follows:

$\begin{matrix}{{{{Re}(y)} = \begin{bmatrix}{- {{Re}\left( G_{1} \right)}} \\\vdots \\{- {{Re}\left( G_{k} \right)}}\end{bmatrix}},{{{Im}(y)} = \begin{bmatrix}{- {{Im}\left( G_{1} \right)}} \\\vdots \\{- {{Im}\left( G_{k} \right)}}\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 86} \right\rbrack\end{matrix}$

Combining the real and imaginary parts results in the expression for theb vector as follows:

$\begin{matrix}\begin{matrix}{b = {{{{Re}(X)}^{T}W\;{{Re}(y)}} + {{{Im}(X)}^{T}W\;{{Im}(y)}}}} \\{= \begin{bmatrix}{- {\sum\limits_{i = 1}^{k}{w_{i}{{Re}\left( G_{i} \right)}\omega_{i}^{- 2}}}} \\{- {\sum\limits_{i = 1}^{k}{w_{i}\left( {{{Im}\left( G_{i} \right)} + {{{Re}\left( G_{i} \right)}\omega_{i}^{- 1}}} \right.}}} \\{\sum\limits_{i = 1}^{k}{{w_{i}\left( {{{Re}\left( G_{i} \right)}^{2} + {{Im}\left( G_{i} \right)}^{2}} \right)}\omega_{i}^{- 2}}}\end{bmatrix}}\end{matrix} & \left\lbrack {{EQ}\#\mspace{14mu} 87} \right\rbrack\end{matrix}$

Implementing Acoustic Volume Sensing

Collecting the Frequency Response Data and Computing the ComplexResponse

To implement volume sensor assembly 148, volume sensor assembly 148should determine the relative response of reference microphone 626 andinvariable volume microphone 630 to the acoustic wave set up by speakerassembly 622. This may be accomplished by driving speaker assembly 622with a sinusoidal output at a known frequency; the complex response ofmicrophones 626, 630 may then be found at that driving frequency.Finally, the relative response of microphones 626, 630 may be found andcorrected for alternating sampling by e.g., an analog-to-digitalconvertor (i.e., ADC).

Additionally, the total signal variance may be computed and compared tothe variance of pure tone extracted using the discrete Fourier transform(i.e., DFT). This may result in a measure of how much of the signalpower comes from noise sources or distortion. This value may then beused to reject and repeat bad measurements.

Computing the Discrete Fourier Transform

The signal from the microphone may be sampled synchronously with theoutput to speaker assembly 622 such that a fixed number of points, N,are taken per wavelength. The measured signal at each point in thewavelength may be summed over an integer number of wavelengths, M, andstored in an array x by the ISR for processing after all the data forthat frequency has been collected.

A DFT may be performed on the data at the integer value corresponding tothe driven frequency of the speaker. The general expression for thefirst harmonic of a DFT is as follows:

$\begin{matrix}{x_{k} = {\frac{2}{MN}{\sum\limits_{n = 0}^{N - 1}{x_{n}{\mathbb{e}}^{{- \frac{2\pi\;{\mathbb{i}}}{N}}{kn}}}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 88} \right\rbrack\end{matrix}$

The product MN may be the total number of points and the factor of twomay be added such that the resulting real and imaginary portions of theanswer match the amplitude of the sine wave:

$\begin{matrix}{x_{n} = {{{{re}\left( x_{k} \right)}{\cos\left( {\frac{2\pi}{N}{kn}} \right)}} + {{{im}\left( x_{k} \right)}{\sin\left( {\frac{2\pi}{N}{kn}} \right)}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 89} \right\rbrack\end{matrix}$

This real part of this expression may be as follows:

$\begin{matrix}{{{re}(x)} = {\frac{2}{MN}{\sum\limits_{n = 0}^{N - 1}{x_{n}{\cos\left( {\frac{2\pi}{N}n} \right)}}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 90} \right\rbrack\end{matrix}$

We may take advantage of the symmetry of the cosine function to reducethe number of computations needed to compute the DFT. The expressionabove may be equivalent to:

$\begin{matrix}{{{re}(x)} = {\frac{2}{MN}\begin{bmatrix}{\left( {x_{0} - x_{\frac{1}{2\;}N}} \right) + {\sum\limits_{n = 1}^{{\frac{1}{4}N} - 1}{\sin\left( {\frac{\pi}{2} - {\frac{2\pi}{N}n}} \right)}}} \\\left\lbrack {\left( {x_{n} - x_{{\frac{1}{2}N} + n}} \right) - \left( {x_{{\frac{1}{2\;}N} + n} - x_{N - n}} \right)} \right\rbrack\end{bmatrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 91} \right\rbrack\end{matrix}$

Similarly, for the imaginary portion of the equation:

$\begin{matrix}{{{im}(x)} = {{- \frac{2}{MN}}{\sum\limits_{n = 0}^{N - 1}{x_{n}{\sin\left( {\frac{2\pi}{N}n} \right)}}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 92} \right\rbrack\end{matrix}$

which may be expressed as follows:

$\begin{matrix}{{{im}(x)} = {- {\frac{2}{MN}\begin{bmatrix}{\left( {x_{\frac{1}{4}N} - x_{\frac{3}{4}N}} \right) +} \\{\sum\limits_{n = 1}^{{\frac{1}{4}N} - 1}{\sin\left( {\frac{2\pi}{N}n} \right)}} \\\left\lbrack {\left( {x_{n} - x_{{\frac{1}{2}N} + n}} \right) + \left( {x_{{\frac{1}{2}N} + n} - x_{N - n}} \right)} \right\rbrack\end{bmatrix}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 93} \right\rbrack\end{matrix}$

The variance of this signal may be calculated as follows:

$\begin{matrix}{\sigma^{2} = {\frac{1}{2}\left( {{{re}(x)}^{2} + {{im}(x)}^{2}} \right)}} & \left\lbrack {{EQ}\#\mspace{14mu} 94} \right\rbrack\end{matrix}$

The maximum possible value of the real and imaginary portions of x maybe 2¹¹; which corresponds to half the AD range. The maximum value of thetone variance may be 2²¹; half the square of the AD range.

Computing the Signal Variance

The pseudo-variance of the signal may be calculated using the followingrelation:

$\begin{matrix}{\sigma^{2} = {{\frac{1}{{NM}^{2}}{\sum\limits_{n = 0}^{N - 1}x_{n}^{2}}} - {\frac{1}{N^{2}M^{2}}\left( {\sum\limits_{n = 0}^{N - 1}x_{n}} \right)^{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 95} \right\rbrack\end{matrix}$

The result may be in the units of AD counts squared. It may only be the“pseudo-variance” because the signal has been averaged over M periodsbefore the variance is calculated over the N samples in the “averaged”period. This may be a useful metric, however, for finding if the“averaged” signal looks like a sinusoid at the expected frequency. Thismay be done by comparing the total signal variance to that of thesinusoid found in the discrete Fourier transform.

The summation may be on the order of

${\sum\limits_{n = 0}^{N - 1}x_{n}^{2}} = {O\left( {{NM}^{2}2^{24}} \right)}$for a 12-bit ADC. If N<2⁷=128 and M<2⁶=64, then the summation will beless than 2⁴³ and may be stored in a 64-bit integer. The maximumpossible value of the variance may result if the ADC oscillated betweena value of 0 and 2¹² on each consecutive sample. This may result in apeak variance of

${\frac{1}{4}\left( 2^{12} \right)^{2}} = 2^{22}$so the result may be stored at a maximum of a ½⁹ resolution in a signed32-bit integer.

Computing the Relative Microphone Response

The relative response (G) of microphones 626, 630 may be computed fromthe complex response of the individual microphones:

$\begin{matrix}{G = {\frac{x_{var}}{x_{ref}} = {\frac{x_{var}}{x_{ref}}\frac{x_{ref}^{\star}}{x_{ref}^{\star}}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 96} \right\rbrack \\{{{Re}(G)} = \frac{{{{Re}\left( x_{var} \right)}{{Re}\left( x_{ref} \right)}} + {{{Im}\left( x_{var} \right)}{{Im}\left( x_{ref} \right)}}}{{{Re}\left( x_{ref} \right)}^{2} + {{Im}\left( x_{ref} \right)}^{2}}} & \left\lbrack {{EQ}\#\mspace{14mu} 97} \right\rbrack \\{{{Im}(G)} = \frac{{{{Re}\left( x_{ref} \right)}{{Im}\left( x_{var} \right)}} - {{{Re}\left( x_{var} \right)}{{Im}\left( x_{ref} \right)}}}{{{Re}\left( x_{ref} \right)}^{2} + {{Im}\left( x_{ref} \right)}^{2}}} & \left\lbrack {{EQ}\#\mspace{14mu} 98} \right\rbrack\end{matrix}$

The denominator of either expression may be expressed in terms of thereference tone variance computed in the previous section as follows:Re(x _(ref))² +Im(x _(ref))²=2σ_(ref) ²  [EQ#99]

Correcting for A/D Skew

The signals from microphones 626, 630 may not be sampled simultaneously;the A/D ISR alternates between microphones 626, 630, taking a total of Nsamples per wavelength for each of microphones 626, 630. The result maybe a phase offset between two microphones 626, 630 of π/N. To correctfor this phase offset, a complex rotation may be applied to the relativefrequency response computed in the previous section:

$\begin{matrix}{G_{rotated} = {G \cdot \left( {{\cos\left( \frac{\pi}{N} \right)} + {{\mathbb{i}}\;{\sin\left( \frac{\pi}{N} \right)}}} \right)}} & \left\lbrack {{EQ}\#\mspace{14mu} 100} \right\rbrack\end{matrix}$

Reference Models

Second and Higher Order Models

Leakage through the seals (e.g., seal assembly 1404) of volume sensorchamber 620 may be modeled as a second resonant port (e.g., port 1504,FIG. 100) connected to an external volume (e.g., external volume 1506,FIG. 100).

The system of equations describing the three-chamber configuration maybe as follows:

$\begin{matrix}{{{\overset{.}{p}}_{1} + {\frac{\rho\; a^{2}}{V_{1}}\left( {{\overset{.}{v}}_{k} - {\overset{.}{v}}_{r\; 12}} \right)}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 101} \right\rbrack \\{{{\overset{.}{p}}_{2} + {\frac{\rho\; a^{2}}{V_{2}}\left( {{\overset{.}{v}}_{r\; 12} - {\overset{.}{v}}_{r\; 23}} \right)}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 102} \right\rbrack \\{{\overset{¨}{v}}_{r\; 12} = {{{- \frac{f_{12}A_{12}}{L_{12}}}{\overset{.}{v}}_{r\; 12}} + {\frac{A_{12}}{\rho\; L_{12}}\left( {p_{2} - p_{1}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 103} \right\rbrack \\{{{\overset{.}{p}}_{3} + {\frac{\rho\; a^{2}}{V_{3}}{\overset{.}{v}}_{r\; 23}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 104} \right\rbrack \\{{\overset{¨}{v}}_{r\; 23} = {{{- \frac{f_{23}A_{23}}{L_{23}}}{\overset{.}{v}}_{r\; 23}} + {\frac{A_{23}}{\rho\; L_{23}}\left( {p_{3} - p_{2}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 105} \right\rbrack\end{matrix}$

Putting these equations into state-space results in the following:

$\begin{matrix}{\begin{bmatrix}{\overset{.}{p}}_{1} \\{\overset{.}{p}}_{2} \\{\overset{.}{p}}_{3} \\{\overset{¨}{v}}_{12} \\{\overset{¨}{v}}_{23}\end{bmatrix} = {{\begin{bmatrix}0 & 0 & 0 & \frac{\rho\; a^{2}}{V_{1}} & 0 \\0 & 0 & 0 & {- \frac{\rho\; a^{2}}{V_{2}}} & \frac{\rho\; a^{2}}{V_{2}} \\0 & 0 & 0 & 0 & {- \frac{\rho\; a^{2}}{V_{3}}} \\{- \frac{A_{12}}{\rho\; L_{12}}} & \frac{A_{12}}{\rho\; L_{12}} & 0 & {- b_{12}} & 0 \\0 & {- \frac{A_{23}}{\rho\; L_{23}}} & \frac{A_{23}}{\rho\; L_{23}} & 0 & {- b_{23}}\end{bmatrix}\left\lbrack \begin{matrix}p_{1} \\p_{2} \\p_{3} \\v_{12} \\v_{23}\end{matrix} \right\rbrack} + {\quad{\left\lbrack \begin{matrix}{- \frac{\rho\; a^{2}}{V_{1}}} \\0 \\0 \\0 \\0\end{matrix} \right\rbrack\left\lbrack {\overset{.}{v}}_{k} \right\rbrack}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 106} \right\rbrack\end{matrix}$

the frequency response of which may be represented graphically in theBode diagram shown in FIG. 101 and which may also be written in transferfunction form:

$\begin{matrix}{\frac{p_{2}}{p_{1}} = \frac{\omega_{12}^{2}\left( {s^{2} + {b_{23}s} + \omega_{23}^{2}} \right)}{\begin{matrix}{{\left( {s^{2} + {b_{12}s} + \omega_{12}^{2}} \right)\left( {s^{2} + {b_{23}s} + \omega_{23}^{2}} \right)} +} \\{\frac{V_{3}}{V_{2}}{\omega_{23}^{2}\left( {s + b_{12}} \right)}s}\end{matrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 107} \right\rbrack\end{matrix}$

Expanding the denominator results in the following:

$\begin{matrix}{\frac{p_{2}}{p_{1}} = \frac{\omega_{12}^{2}\left( {s^{2} + {b_{23}s} + \omega_{23}^{2}} \right)}{\begin{matrix}{s^{4} + {\left( {b_{12} + b_{23}} \right)s^{3}} + {\left( {{b_{12}b_{23}} + \omega_{12}^{2} + {\omega_{23}^{2}\left( {1 + \frac{V_{3}}{V_{2}}} \right)}} \right)s^{2}} +} \\{{\left( {{b_{23}\omega_{12}^{2}} + {b_{12}{\omega_{23}^{2}\left( {1 + \frac{V_{3}}{V_{2}}} \right)}}} \right)s} + {\omega_{12}^{2}\omega_{23}^{2}}}\end{matrix}}} & \left\lbrack {{EQ}\#\mspace{14mu} 108} \right\rbrack\end{matrix}$

A bubble underneath the diaphragm material in the variable volume willfollow the same dynamic equations as a leakage path. In this case, thediaphragm material may act as the resonant mass rather than the leakageport. Accordingly, the equation may be as follows:m{umlaut over (x)}=ΔpA−b _(m) {dot over (x)}  [EQ#109]

wherein m is the mass of the diaphragm, A is the cross sectional area ofthe diaphragm that can resonate, and b_(m) is the mechanical damping.EQ#106 may be written in terms of the volume flow rate:

$\begin{matrix}{\overset{¨}{v} = {{{- \frac{b}{m}}\overset{.}{v}} + {\Delta\; p\frac{A^{2}}{m}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 110} \right\rbrack\end{matrix}$

wherein the volume of the air bubble is V₃. If the bubble volume issubstantially smaller than the acoustic volume V₃<<V₂ than the transferfunction may be simplified to:

$\begin{matrix}{\frac{p_{2}}{p_{1}} = \frac{\omega_{12}^{2}\left( {s^{2} + {b_{23}s} + \omega_{23}^{2}} \right)}{\left( {s^{2} + {b_{12}s} + \omega_{12}^{2}} \right)\left( {s^{2} + {b_{23}s} + {\omega_{23}^{2}\left( {1 + \frac{V_{3}}{V_{2}}} \right)}} \right)}} & \left\lbrack {{EQ}\#\mspace{14mu} 111} \right\rbrack\end{matrix}$

Second Order with Time Delay

The volume sensor assembly 148 equations derived above assume that thepressure is the same everywhere in the acoustic volume. This is only anapproximation, as there are time delays associated with the propagationof the sound waves through the volume. This situation may look like atime delay or a time advance based on the relative position of themicrophone and speakers.

A time delay may be expressed in the Laplace domain as:G(s)=e ^(−ΔTs)  [EQ#112]

which makes for a non-linear set of equations. However, a first-orderPade approximation of the time delay may be used as follows:

$\begin{matrix}{{G(s)} = {- \frac{s + \frac{2}{\Delta\; T}}{s - \frac{2}{\Delta\; T}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 113} \right\rbrack\end{matrix}$

which is shown graphically in FIG. 102.

Three Chamber Volume Estimation

Volume sensor assembly 148 may also be configured using a thirdreference volume (e.g., reference volume 1508; FIG. 103) connected witha separate resonant port (e.g., port 1510; FIG. 103). This configurationmay allow for temperature-independent volume estimation.

The system of equations describing the three-chamber configuration areas follows:

$\begin{matrix}{{{\overset{.}{p}}_{1} + {\frac{\rho\; a^{2}}{V_{1}}\left( {{\overset{.}{v}}_{k} - {\overset{.}{v}}_{r\; 12} - {\overset{.}{v}}_{r\; 13}} \right)}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 114} \right\rbrack \\{{{\overset{.}{p}}_{2} + {\frac{\rho\; a^{2}}{V_{2}}{\overset{.}{v}}_{r\; 12}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 115} \right\rbrack \\{{\overset{¨}{v}}_{r\; 12} = {{{- \frac{f_{12}A_{12}}{L_{12}}}{\overset{.}{v}}_{r\; 12}} + {\frac{A_{12}}{\rho\; L_{12}}\left( {p_{2} - p_{1}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 116} \right\rbrack \\{{{\overset{.}{p}}_{3} + {\frac{\rho\; a^{2}}{V_{3}}{\overset{.}{v}}_{r\; 13}}} = 0} & \left\lbrack {{EQ}\#\mspace{14mu} 117} \right\rbrack \\{{\overset{¨}{v}}_{r\; 13} = {{{- \frac{f_{13}A_{13}}{L_{13}}}{\overset{.}{v}}_{r\; 13}} + {\frac{A_{13}}{\rho\; L_{13}}\left( {p_{2} - p_{1}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 118} \right\rbrack\end{matrix}$

Using these equations and solving for the transfer function across eachof the resonant ports results in the following:

$\begin{matrix}{{\frac{p_{2}}{p_{1}} = \frac{\omega_{n\; 12}^{2}}{s^{2} + {2\;\zeta_{12}\omega_{n\; 12}s} + \omega_{n\; 12}^{2}}}{where}} & \left\lbrack {{EQ}\#\mspace{14mu} 119} \right\rbrack \\{\omega_{n\; 12} = {{\frac{1}{V_{2}}\frac{a^{2}A_{12}}{L_{12}}\mspace{14mu}{and}\mspace{14mu}\zeta} = \frac{f_{12}A_{12}}{2\; L_{12}\omega_{n\; 12}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 120} \right\rbrack \\{{\frac{p_{3}}{p_{1}} = \frac{\omega_{n\; 13}^{2}}{s^{2} + {2\;\zeta_{13}\omega_{n\; 13}s} + \omega_{n\; 13}^{2}}}{where}} & \left\lbrack {{EQ}\#\mspace{14mu} 121} \right\rbrack \\{\omega_{n\; 13} = {{\frac{1}{V_{3}}\frac{a^{2}A_{13}}{L_{13}}\mspace{14mu}{and}\mspace{14mu}\zeta} = \frac{f_{13}A_{13}}{2L_{13}\omega_{n\; 13}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 122} \right\rbrack\end{matrix}$

The volume of volume sensor chamber 620 may be estimated using the ratioof the natural frequency of the two resonant ports as follows:

$\begin{matrix}{\frac{\omega_{n\; 13}^{2}}{\omega_{n\; 12}^{2}} = {\frac{V_{2}}{V_{3}}\frac{A_{13}}{A_{12}}\frac{L_{12}}{L_{13}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 123} \right\rbrack\end{matrix}$

EQ#120 illustrates that the volume of volume sensor chamber 620 may beproportional to reference volume 1508. The ratio of these two volumes(in the ideal model) may only depend on the geometry of the resonantport (e.g., port 1510; FIG. 103) and has no dependence upon temperature.

Exponential Volume Model

Assume the flow out through the flow resistance has the following form:

$\begin{matrix}{{\overset{.}{V}}_{out} = \frac{V_{avs}}{\tau}} & \left\lbrack {{EQ}\#\mspace{14mu} 124} \right\rbrack\end{matrix}$

Assuming a fixed input flow rate from the pump chamber, the volume ofvolume sensor chamber 620 is based upon the following differentialequation:

$\begin{matrix}{{\overset{.}{V}}_{avs} = {{{\overset{.}{V}}_{in} - {\overset{.}{V}}_{out}} = {{\overset{.}{V}}_{in} - \frac{V_{avs}}{\tau}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 125} \right\rbrack\end{matrix}$

which gives the following solution assuming a zero initial volume:

$\begin{matrix}{V_{avs} = {{\overset{.}{V}}_{in}{\tau\left( {1 - {\mathbb{e}}^{- \frac{t}{\tau}}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 126} \right\rbrack\end{matrix}$

Accordingly, the output flow rate flows:

$\begin{matrix}{{\overset{.}{V}}_{out} = {{\overset{.}{V}}_{in}\left( {1 - {\mathbb{e}}^{- \frac{t}{\tau}}} \right)}} & \left\lbrack {{EQ}\#\mspace{14mu} 127} \right\rbrack\end{matrix}$

The volume delivered during the pump phase may be written:

$\begin{matrix}{V_{out} = {{\overset{.}{V}}_{in}\left\lbrack {t - {\tau\left( {1 - {\mathbb{e}}^{- \frac{t}{\tau}}} \right)}} \right\rbrack}} & \left\lbrack {{EQ}\#\mspace{14mu} 128} \right\rbrack\end{matrix}$

Device Calibration

The model fit allows the resonant frequency of the port to be extractedfrom the sine sweep data. The next step is to relate this value to thedelivered volume. The ideal relationship between the resonant frequencyand the delivered volume to be expressed as follows:

$\begin{matrix}{\omega_{n}^{2} = {\frac{a^{2}A}{L}\frac{1}{V_{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 129} \right\rbrack\end{matrix}$

The speed of sound will vary with temperature, so it may be useful tosplit out the temperature effects.

$\begin{matrix}{\omega_{n}^{2} = {\frac{\gamma\;{RA}}{L}\frac{T}{V_{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 130} \right\rbrack\end{matrix}$

The volume may then be expressed as a function of the measured resonantfrequency and the temperature:

$\begin{matrix}{V_{2} = {C\frac{T}{\omega_{n}^{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 131} \right\rbrack\end{matrix}$

Where c is the calibration constant

$C = \frac{\gamma\;{RA}}{L}$

Implementation Details

End Effects

The air resonating in the port (e.g., port assembly 624) may extend outinto the acoustic volumes at the end of each oscillation. The distancethe air extends may be estimated based on the fundamental volume sensorassembly equations. For any given acoustic volume, the distance the airextends into the volume may be expressed as a function of the pressureand port cross-sectional area:

$\begin{matrix}{x = {\frac{V}{\rho\; a^{2}A}p}} & \left\lbrack {{EQ}\#\mspace{14mu} 132} \right\rbrack\end{matrix}$

If we assume the following values:

$\begin{matrix}{V = {28.8 \times 10^{- 6}L}} & \left\lbrack {{EQ}\#\mspace{14mu} 133} \right\rbrack \\{\rho = {1.292\mspace{14mu}\frac{kg}{m^{3}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 134} \right\rbrack \\{a = {340\mspace{14mu}\frac{m}{s}}} & \left\lbrack {{EQ}\#\mspace{14mu} 135} \right\rbrack \\{d = {0.5 \cdot {mm}}} & \left\lbrack {{EQ}\#\mspace{14mu} 136} \right\rbrack \\{p = {{1 \cdot P}\; a\mspace{14mu}\left( {{Approximately}\mspace{14mu} 100\mspace{14mu}{dB}} \right)}} & \left\lbrack {{EQ}\#\mspace{14mu} 137} \right\rbrack\end{matrix}$

Accordingly, the air will extend roughly 1.9 mm in to the acousticchamber.

Sizing V1 (i.e., the Fixed Volume) Relative to V2 (i.e., the VariableVolume)

Sizing V₁ (e.g., fixed volume 1500) may require trading off acousticvolume with the relative position of the poles and zeros in the transferfunction. The transfer function for both V₁ and V₂ (e.g., variablevolume 1502) are shown below relative to the volume displacement ofspeaker assembly 622.

$\begin{matrix}{\frac{p_{2}}{v_{k}} = {{- \frac{\rho\; a^{2}}{V_{1}}}\frac{\omega_{n}^{2}}{s^{2} + {2\;\zeta\;\omega_{n}s} + {\alpha\omega}_{n}^{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 138} \right\rbrack \\{{\frac{p_{1}}{v_{k}} = {{- \frac{\rho\; a^{2}}{V_{1}}}\frac{s^{2} + {2\;{\zeta\omega}_{n}s} + {\alpha\omega}_{n}^{2}}{s^{2} + {2\;\zeta\;\omega_{n}s} + \omega_{n}^{2}}}}{where}} & \left\lbrack {{EQ}\#\mspace{14mu} 139} \right\rbrack \\{{\omega_{n}^{2} = {\frac{a^{2}A}{L}\frac{1}{V_{2}}}},{\zeta = {{\frac{fA}{2\; L\;\omega_{n}}\mspace{14mu}{and}\mspace{14mu}\alpha} = \left( {1 + \frac{V_{2}}{V_{1}}} \right)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 140} \right\rbrack\end{matrix}$

As V₁ is increased the gain may decrease and the speaker may be drivenat a higher amplitude to get the same sound pressure level. However,increasing V₁ may also have the benefit of moving the complex zeros inthe p₁ transfer function toward the complex poles. In the limiting casewhere V₁→∞, α→1 and you have pole-zero cancellation and a flat response.Increasing V₁, therefore, may have the benefit of reducing both theresonance and the notch in the p₁ transfer function, and moving the p₂poles toward ω_(n); resulting in a lower sensitivity to measurementerror when calculating the p₂/p₁ transfer function.

FIG. 104 is a graphical representation of:

$\begin{matrix}\frac{p_{1}}{v_{k}} & \left\lbrack {{EQ}\#\mspace{14mu} 141} \right\rbrack\end{matrix}$

FIG. 105 is a graphical representation of

$\begin{matrix}\frac{p_{2}}{v_{k}} & \left\lbrack {{EQ}\#\mspace{14mu} 142} \right\rbrack\end{matrix}$

Aliasing

Higher frequencies may alias down to the frequency of interest, whereinthe aliased frequency may be expressed as follows:f=|f _(n) −nf _(s)|  [EQ#143]

where f_(s) is the sampling frequency, f_(n) is the frequency of thenoise source, n is a positive integer, and f is the aliased frequency ofthe noise source.

The demodulation routine may effectively filter out noise except at thespecific frequency of the demodulation. If the sample frequency is setdynamically to be a fixed multiple of the demodulation frequency, thenthe frequency of the noise that can alias down to the demodulationfrequency may be a fixed set of harmonics of that fundamental frequency.

For example, if the sampling frequency is eight times the demodulationfrequency, then the noise frequencies that can alias down to thatfrequency are as follows:

$\begin{matrix}{\begin{matrix}{\frac{f_{n}}{f} = \left\{ {\frac{1}{{n\;\beta} + 1},\frac{1}{{n\;\beta} - 1}} \right\}} \\{= \left\{ {\frac{1}{7},\frac{1}{9},\frac{1}{15},\frac{1}{17},\frac{1}{23},\frac{1}{25},\ldots} \right\}}\end{matrix}{{{where}\mspace{14mu}\beta} = {\frac{f_{s}}{f} = 8.}}} & \left\lbrack {{EQ}\#\mspace{14mu} 144} \right\rbrack\end{matrix}$For β=16, the following series would result:

$\begin{matrix}{\frac{f_{n}}{f} = \left\{ {\frac{1}{15},\frac{1}{17},\frac{1}{31},\frac{1}{33},\ldots} \right\}} & \left\lbrack {{EQ}\#\mspace{14mu} 145} \right\rbrack\end{matrix}$

Performance

Sensitivity to Temperature

The sensitivity to temperature may be split into a gain change and anoise change. If the temperature is off by a factor of dT, the resultinggain error may be:

$\begin{matrix}{V_{2} = {c\left( {\frac{T_{2}}{\omega_{2}^{2}} - \frac{T_{1}}{\omega_{1}^{2}}} \right)}} & \left\lbrack {{EQ}\#\mspace{14mu} 147} \right\rbrack\end{matrix}$

Accordingly, if the same temperature is used for both sine sweeps, anyerror in the temperature measurement may look like a gain change to thesystem.

$\begin{matrix}{e_{gain} = {1 - \frac{T_{measured}}{T_{actual}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 148} \right\rbrack\end{matrix}$

Therefore, for a 1° K temperature error, the resulting volume error maybe 0.3% at 298° K. This error may include both the error in thetemperature sensor and the difference between the sensor temperature andthe temperature of the air within volume sensor assembly 148.

The measurement, however, may be more susceptible to noise in thetemperature measurement. A temperature change during the differentialsine sweeps may result in an error that looks more like an offset ratherthan a gain change:

$\begin{matrix}{V_{error} = {\frac{c}{\omega^{2}}\Delta\; T}} & \left\lbrack {{EQ}\#\mspace{14mu} 149} \right\rbrack\end{matrix}$

Accordingly, if the measurement varies by 0.1 K during the twomeasurement sine sweeps, the difference may be 0.012 uL. Therefore, itmay be better to use a consistent temperature estimate for each deliveryrather than taking a separate temperature measurement for each sinesweep (as shown in FIG. 107).

The LM73 temperature sensor has a published accuracy of +/−1° C. and aresolution of 0.03 C. Further, the LM73 temperature sensor seems toconsistently have a startup transient of about 0.3° C. that takes aboutfive sine sweeps to level out (as shown in FIG. 108).

Since the above-described infusion pump assemblies (e.g., infusion pumpassembly 100, 100′, 400, 500) provides discrete deliveries of infusiblefluid, the above-described infusion pump assemblies may be modeledentirely in the discrete domain (in the manner shown in FIG. 109), whichmay be reduced to the following:

$\begin{matrix}{{G_{p}(z)} = \frac{Kz}{z - 1}} & \left\lbrack {{EQ}\#\mspace{14mu} 150} \right\rbrack\end{matrix}$

A discrete-time PI regulator may perform according to the following:

$\begin{matrix}{{G_{c}(z)} = {K_{p}\left( {1 + {\frac{T_{s}}{T_{I}}\frac{z}{z - 1}}} \right)}} & \left\lbrack {{EQ}\#\mspace{14mu} 151} \right\rbrack\end{matrix}$

The AVS system described above works by comparing the acoustic responsein fixed volume 1500 and variable volume 1502 to a speaker driven inputand extracting the volume of the variable volume 1502. As such, there isa microphone in contact with each of these separate volumes (e.g.,microphones 626, 630). The response of variable volume microphone 630may also be used in a more gross manner to detect the presence orabsence of disposable housing assembly 114. Specifically, if disposablehousing assembly 114 is not attached to (i.e., positioned proximate)variable volume 1502, essentially no acoustic response to the speakerdriven input should be sensed. The response of fixed volume 1500,however, should remain tied to the speaker input. Thus, the microphonedata may be used to determine whether disposable housing assembly 114 bysimply ensuring that both microphones exhibit an acoustic response. Inthe event that microphone 626 (i.e., the microphone positioned proximatefixed volume 1500) exhibits an acoustic response and microphone 630(i.e., the microphone positioned proximate variable volume 1502) doesnot exhibit an acoustic response, it may be reasonably concluded thatdisposable housing assembly 114 is not attached to reusable housingassembly 102. It should be noted that a failure of variable volumemicrophone 630 may also appear to be indicative of disposable housingassembly 114 not being attached, as the failure of variable volumemicrophone 630 may result in a mid-range reading that is nearlyindistinguishable from the microphone response expected when disposablehousing assembly 114 is not attached.

For the following discussion, the following nomenclature may be used:

Symbols α_(max)(f) maximum read at a given frequency α_(min)(f) minimumread at a given frequency δ difference between max and min sums findividual frequency F set of sine sweep frequencies N number offrequencies in each sine sweep, F φ boolean disposable attached flagσmax sum of maximum ADC reads σmin sum of minimum ADC reads T max/minADC difference threshold Subscripts i sweep number ref reference volumevar variable volume

As part of the demodulation routine employed in each frequency responsecalculation, the minimum and maximum readings of both fixed volumemicrophone 626 and variable volume microphone 630 may be calculated. Thesum of these maximum and minimum values may be calculated over theentire sine-sweep (as discussed above) for both microphone 626 andmicrophone 630 as follows.

$\begin{matrix}{{\sigma\;\max} = {\sum\limits^{f \in F}{\alpha_{\max}(f)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 152} \right\rbrack \\{{\sigma\;\min} = {\sum\limits^{f \in \; F}{\alpha_{\min}(f)}}} & \left\lbrack {{EQ}\#\mspace{14mu} 153} \right\rbrack\end{matrix}$

and the difference between these two summations may be simplified asfollows:δ=σmax−σmin  [EQ#154]

While δ may be divided by the number of sine sweeps to get the averageminimum/maximum difference for the sine sweep (which is then compared toa threshold), the threshold may equivalently be multiplied by N forcomputational efficiency. Accordingly, the basic disposable detectionalgorithm may be defined as follows:

$\begin{matrix}{\phi_{i} = \left\{ \begin{matrix}1 & {{{if}\mspace{14mu}\delta_{var}} > {N \star T}} \\0 & {{{{{{if}\mspace{14mu}\delta_{var}} < {N \star T}}\&}\mspace{11mu}\delta_{ref}} > {N \star T}}\end{matrix} \right.} & \left\lbrack {{EQ}\#\mspace{14mu} 155} \right\rbrack\end{matrix}$

The additional condition that the maximum/minimum difference be greaterthan the threshold is a check performed to ensure that a failed speakeris not the cause of the acoustic response received. This algorithm maybe repeated for any sine-sweep, thus allowing a detachment of disposablehousing assembly 114 to be sensed within e.g., at most two consecutivesweeps (i.e., in the worst case scenario in which disposable housingassembly 114 is removed during the second half of an in-progress sinesweep).

Thresholding for the above-described algorithm may be based entirely onnumerical evidence. For example, examination of typical minimum/maximumresponse differences may show that no individual difference is ever lessthan five hundred ADC counts. Accordingly, all data examined whiledisposable housing assembly 114 is detached from reusable housingassembly 102 may show that all minimum/maximum response differences asbeing well under five hundred ADC counts. Thus, the threshold for δ maybe set at T=500.

While volume sensor assembly 148 is described above as being utilizedwithin an infusion pump assembly (e.g., infusion pump assembly 100),this is for illustrative purposes only and is not intended to be alimitation of this disclosure, as other configurations are possible andare considered to be within the scope of this disclosure. For example,volume sensor assembly 148 may be used within a process controlenvironment for e.g., controlling the quantity of chemicals mixedtogether. Alternatively, volume sensor assembly 148 may be used within abeverage dispensing system to control e.g., the quantity of ingredientsmixed together.

While volume sensor assembly 148 is described above as utilizing a port(e.g., port assembly 624) as a resonator, this is for illustrativepurposes only, as other configurations are possible and are consideredto be within the scope of this disclosure. For example, a solid mass(not shown) may be suspended within port assembly 624 and may functionas a resonator for volume sensor assembly 148. Specifically, the mass(not shown) for the resonator may be suspended on a diaphragm (notshown) spanning port assembly 624. Alternatively, the diaphragm itself(not shown) may act as the mass for the resonator. The natural frequencyof volume sensor assembly 148 may be a function of the volume ofvariable volume 1502. Accordingly, if the natural frequency of volumesensor assembly 148 can be measured, the volume of variable volume 1502may be calculated.

The natural frequency of volume sensor assembly 148 may be measured in anumber of different ways. For example, a time-varying force may beapplied to the diaphragm (not shown) and the relationship between thatforce and the motion of the diaphragm (not shown) may be used toestimate the natural frequency of volume sensor assembly 148.Alternately the mass (not shown) may be perturbed and then allowed tooscillate. The unforced motion of the mass (not shown) may then be usedto calculate the natural frequency of volume sensor assembly 148.

The force applied to the resonant mass (not shown) may be accomplishedin various ways, examples of which may include but are not limited to:

-   -   speaker assembly 622 may create a time-varying pressure within        fixed volume 1500;    -   the resonant mass (not shown) may be a piezoelectric material        responding to a time-varying voltage/current; and    -   the resonant mass (not shown) may be a voice coil responding to        a time-varying voltage/current

The force applied to the resonant mass may be measured in various ways,examples of which may include but are not limited to:

-   -   measuring the pressure in the fixed volume;    -   the resonant mass (not shown) may be a piezoelectric material;        and    -   a strain gauge may be connected to the diaphragm (not shown) or        other structural member supporting the resonant mass (not        shown).

Similarly, the displacement of the resonant mass (not shown) may beestimated by measuring the pressure in the variable volume, or measureddirectly in various ways, examples of which may include but are notlimited to:

-   -   via piezoelectric sensor;    -   via capacitive sensor;    -   via optical sensor;    -   via Hall-effect sensor;    -   via a potentiometer (time varying impedance) sensor;    -   via an inductive type sensor; and    -   via a linear variable differential transformer (LVDT)

Further, the resonant mass (not shown) may be integral to either theforce or displacement type sensor (i.e. the resonant mass (not shown)may be made of piezoelectric material).

The application of force and measurement of displacement may beaccomplished by a single device. For example, a piezoelectric materialmay be used for the resonant mass (not shown) and a time-varyingvoltage/current may be applied to the piezoelectric material to create atime-varying force. The resulting voltage/current applied to thepiezoelectric material may be measured and the transfer function betweenthe two used to estimate the natural frequency of volume sensor assembly148.

As discussed above, the resonant frequency of volume sensor assembly 148may be estimated using swept-sine system identification. Specifically,the above-described model fit may allow the resonant frequency of theport assembly to be extracted from the sine sweep data, which may thenbe used to determine the delivered volume. The ideal relationshipbetween the resonant frequency and the delivered volume may be expressedas follows:

$\begin{matrix}{\omega_{n}^{2} = {\frac{a^{2}A}{L}\frac{1}{V_{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 126} \right\rbrack\end{matrix}$

The speed of sound will vary with temperature, so it may be useful tosplit out the temperature effects.

$\begin{matrix}{\omega_{n}^{2} = {\frac{\gamma\;{RA}}{L}\frac{T}{V_{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 126} \right\rbrack\end{matrix}$

The volume may then be expressed as a function of the measured resonantfrequency and the temperature:

$\begin{matrix}{V_{2} = {C\frac{T}{\omega_{n}^{2}}}} & \left\lbrack {{EQ}\#\mspace{14mu} 127} \right\rbrack\end{matrix}$

Where c is the calibration constant

$\begin{matrix}{C = {\frac{\gamma\;{RA}}{L}.}} & \;\end{matrix}$

Infusion pump assembly 100 may then compare this calculated volume V₂(i.e., representative of the actual volume of infusible fluid deliveredto the user) to the target volume (i.e., representative of the quantityof fluid that was supposed to be delivered to the user). For example,assume that infusion pump assembly 100 was to deliver a 0.100 unit basaldose of infusible fluid to the user every thirty minutes. Further,assume that upon effectuating such a delivery, volume sensor assembly148 indicates a calculated volume V₂ (i.e., representative of the actualvolume of infusible fluid delivered to the user) of 0.095 units ofinfusible fluid.

When calculating volume V₂, infusion pump assembly 100 may firstdetermine the volume of fluid within volume sensor chamber 620 prior tothe administration of the dose of infusible fluid and may subsequentlydetermine the volume of fluid within volume sensor chamber 620 after theadministration of the dose of infusible fluid, wherein the difference ofthose two measurements is indicative of V₂ (i.e., the actual volume ofinfusible fluid delivered to the user). Accordingly, V₂ is adifferential measurement.

V2 may be the total air space over the diaphragm in the variable volumechamber. The actual fluid delivery to the patient may be the differencein V2 from when the chamber was full to after the measurement valve wasopened and the chamber was emptied. V2 may not directly be the deliveredvolume. For example, the air volume may be measured and a series ofdifferential measurements may be taken. For occlusion, an emptymeasurement may be taken, the chamber may be filed, a full measurementmay be taken, and then a final measurement may be taken after the exitvalve is open. Accordingly, the difference between the first and secondmeasurement may be the amount pumped and the difference between thesecond and third is the amount delivered to the patient.

Accordingly, electrical control assembly 110 may determine that theinfusible fluid delivered is 0.005 units under what was called for. Inresponse to this determination, electrical control assembly 110 mayprovide the appropriate signal to mechanical control assembly 104 sothat any additional necessary dosage may be pumped. Alternatively,electrical control assembly 110 may provide the appropriate signal tomechanical control assembly 104 so that the additional dosage may bedispensed with the next dosage. Accordingly, during administration ofthe next 0.100 unit dose of the infusible fluid, the output command forthe pump may be modified based on the difference between the target andamount delivered.

Referring also to FIG. 110, there is shown one particular implementationof a control system for controlling the quantity of infusible fluidcurrently being infused based, at least in part, on the quantity ofinfusible fluid previously administered. Specifically and continuingwith the above-stated example, assume for illustrative purposes thatelectrical control assembly 110 calls for the delivery of a 0.100 unitdose of the infusible fluid to the user. Accordingly, electrical controlassembly 110 may provide a target differential volume signal 1600 (whichidentifies a partial basal dose of 0.010 units of infusible fluid percycle of shape memory actuator 112) to volume controller 1602.Accordingly and in this particular example, shape memory actuator 112may need to be cycled ten times in order to achieve the desired basaldose of 0.100 units of infusible fluid (i.e., 10 cycles×0.010 units percycle=0.100 units). Volume controller 1602 in turn may provide “on-time”signal 1606 to SMA (i.e., shape memory actuator) controller 1608. Alsoprovided to SMA controller 1608 is battery voltage signal 1610.

Specifically, shape-memory actuator 112 may be controlled by varying theamount of thermal energy (e.g., joules) applied to shape-memory actuator112. Accordingly, if the voltage level of battery 606 is reduced, thequantity of joules applied to shape-memory actuator 112 may also bereduced for a defined period of time. Conversely, if the voltage levelof battery 606 is increased, the quantity of joules applied to shapememory actuator 112 may also be increased for a defined period of time.Therefore, by monitoring the voltage level of battery 606 (via batteryvoltage signal 1610), the type of signal applied to shape-memoryactuator 112 may be varied to ensure that the appropriate quantity ofthermal energy is applied to shape-memory actuator 112 regardless of thebattery voltage level.

SMA controller 1608 may process “on-time” signal 1606 and batteryvoltage signal 1610 to determine the appropriate SMA drive signal 1612to apply to shape-memory actuator 112. One example of SMA drive signal1612 may be a series of binary pulses in which the amplitude of SMAdrive signal 1612 essentially controls the stroke length of shape-memoryactuator 112 (and therefore pump assembly 106) and the duty cycle of SMAdrive signal 1612 essentially controls the stroke rate of shape-memoryactuator 112 (and therefore pump assembly 106). Further, since SMA drivesignal 1612 is indicative of a differential volume (i.e., the volumeinfused during each cycle of shape memory actuator 112), SMA drivesignal 1612 may be integrated by discrete time integrator 1614 togenerate volume signal 1616 which may be indicative of the totalquantity of infusible fluid infused during a plurality of cycles ofshape memory actuator 112. For example, since (as discussed above) itmay take ten cycles of shape memory actuator 112 (at 0.010 units percycle) to infuse 0.100 units of infusible fluid, discrete timeintegrator 1614 may integrate SMA drive signal 1612 over these tencycles to determine the total quantity infused of infusible fluid (asrepresented by volume signal 1616).

SMA drive signal 1612 may actuate pump assembly 106 for e.g. one cycle,resulting in the filling of volume sensor chamber 620 included withinvolume sensor assembly 148. Infusion pump assembly 100 may then make afirst measurement of the quantity of fluid included within volume sensorchamber 620 (as discussed above). Further and as discussed above,measurement valve assembly 610 may be subsequently energized, resultingin all or a portion of the fluid within volume sensor chamber 620 beingdelivered to the user. Infusion pump assembly 100 may then make ameasurement of the quantity of fluid included within volume sensorchamber 620 (as described above) and use those two measurements todetermine V₂ (i.e., the actual volume of infusible fluid delivered tothe user during the current cycle of shape memory actuator 112). Oncedetermined, V₂ (i.e., as represented by signal 1618) may be provided(i.e., fed back) to volume controller 1602 for comparison to theearlier-received target differential volume.

Continuing with the above-stated example in which the differentialtarget volume was 0.010 units of infusible fluid, assume that V₂ (i.e.,as represented by signal 1618) identifies 0.009 units of infusible fluidas having been delivered to the user. Accordingly, infusion pumpassembly 100 may increase the next differential target volume to 0.011units to offset the earlier 0.001 unit shortage. Accordingly and asdiscussed above, the amplitude and/or duty cycle of SMA drive signal1612 may be increased when delivering the next basal dose of theinfusible fluid to the user. This process may be repeated for theremaining nine cycles of shape memory actuator 112 (as discussed above)and discrete time integrator 1614 may continue to integrate SMA drivesignal 1612 (to generate volume signal 1616) which may define the totalquantity of infusible fluid delivered to the user.

Referring also to FIG. 111, there is shown one possible embodiment ofvolume controller 1602. In this particular implementation, volumecontroller 1602 may include PI (proportional-integrator) controller1650. Volume controller 1602 may include feed forward controller 1652for setting an initial “guess” concerning “on-time” signal 1606. Forexample, for the situation described above in which target differentialvolume signal 1600 identifies a partial basal dose of 0.010 units ofinfusible fluid per cycle of shape memory actuator 112, feed forwardcontroller 1652 may define an initial “on-time” of e.g., onemillisecond. Feed forward controller 1652 may include e.g., a lookuptable that define an initial “on-time” that is based, at least in part,upon target differential volume signal 1600. Volume controller 1602 mayfurther include discrete time integrator 1654 for integrating targetdifferential volume signal 1600 and discrete time integrator 1656 forintegrating V₂ (i.e., as represented by signal 1618).

Referring also to FIG. 112, there is shown one possible embodiment offeed forward controller 1652. In this particular implementation, feedforward controller 1652 may define a constant value signal 1658 and mayinclude amplifier 1660 (e.g., a unity gain amplifier), the output ofwhich may be summed with constant value signal 1658 at summing node1662. The resulting summed signal (i.e., signal 1664) may be provided toas an input signal to e.g., lookup table 1666, which may be processed togenerate the output signal of feed forward controller 1652.

As discussed above, pump assembly 106 may be controlled by shape memoryactuator 112. Further and as discussed above, SMA controller 1608 mayprocess “on-time” signal 1606 and battery voltage signal 1610 todetermine the appropriate SMA drive signal 1612 to apply to shape-memoryactuator 112.

Referring also to FIGS. 113-114, there is shown one particularimplementation of SMA controller 1608. As discussed above, SMAcontroller 1608 may be responsive to “on-time” signal 1606 and batteryvoltage signal 1610 and may provide SMA drive signal 1612 toshape-memory actuator 112. SMA controller 1608 may include a feedbackloop (including unit delay 1700), the output of which may be multipliedwith battery voltage signal 1610 at multiplier 1702. The output ofmultiplier 1702 may be amplified with e.g., unity gain amplifier 1704.The output of amplifier 1704 may be applied to the negative input ofsumming node 1706 (to which “on-time” signal 1606 is applied). Theoutput of summing node 1706 may be amplified (via e.g., unity gainamplifier 1708). SMA controller may also include feed forward controller1710 to provide an initial value for SMA drive signal 1612 (in a fashionsimilar to feed forward controller 1652 of volume controller 1602; SeeFIG. 112). The output of feed forward controller 1710 may be summed atsumming node 1712 with the output of amplifier 1708 and an integratedrepresentation (i.e., signal 1714) of the output of amplifier 1708 toform SMA drive signal 1612.

SMA drive signal 1612 may be provided to control circuitry thateffectuates the application of power to shape-memory actuator 112. Forexample, SMA drive signal 1612 may be applied to switching assembly 1716that may selectively apply current signal 1718 (supplied from battery606) and/or fixed signal 1720 to shape-memory actuator. For example, SMAdrive signal 1612 may effectuate the application of energy (suppliedfrom battery 606 via current signal 1718) via switching assembly 1716 ina manner that achieves the duty cycle defined by SMA drive signal 1612.Unit delay 1722 may generate a delayed version of the signal applied toshape-memory actuator 112 to form battery voltage signal 1610 (which maybe applied to SMA controller 1608).

When applying power to shape-memory actuator 112, voltage may be appliedfor a fixed amount of time and: a) at a fixed duty cycle with anunregulated voltage; b) at a fixed duty cycle with a regulated voltage;c) at a variable duty cycle based upon a measured current value; d) at avariable duty cycle based upon a measured voltage value; and e) at avariable duty cycle based upon the square of a measured voltage value.Alternatively, voltage may be applied to shape-memory actuator 112 for avariable amount of time based upon a measured impedance.

When applying an unregulated voltage for a fixed amount of time at afixed duty cycle, inner loop feedback may not be used and shape memoryactuator may be driven at a fixed duty cycle and with an on-timedetermined by the outer volume loop.

When applying a regulated voltage for a fixed amount of time at a fixedduty cycle, inner loop feedback may not be used and shape memoryactuator 112 may be driven at a fixed duty cycle and with an on-timedetermined by the outer volume loop.

When applying an unregulated voltage at a variable duty cycle based upona measured current value, the actual current applied to shape-memoryactuator 112 may be measured and the duty cycle may be adjusted duringthe actuation of shape-memory actuator 112 to maintain the correct meancurrent.

When applying an unregulated voltage at a variable duty cycle based upona measured voltage value, the actual voltage applied to shape-memoryactuator 112 may be measured and the duty cycle may be adjusted duringthe actuation of shape-memory actuator 112 to maintain the correct meanvoltage.

When applying an unregulated voltage at a variable duty cycle based uponthe square of a measured voltage value, the actual voltage applied toshape-memory actuator 112 may be measured and the duty cycle may beadjusted during the actuation of shape-memory actuator 112 to maintainthe square of the voltage at a level required to provide the desiredlevel of power to shape-memory actuator 112 (based upon the impedance ofshape-memory actuator 112).

Referring also to FIG. 114A-114B, there is shown other implementationsof SMA controller 1608. Specifically, FIG. 114A is an electricalschematic that includes a microprocessor and various control loops thatmay be configured to provide a PWM signal that may open and close theswitch assembly. The switch assembly may control the current that isallowed to flow through the shape memory actuator. The battery mayprovide the current to the shape memory actuator. Further, 114Bdiscloses a volume controller and an inner shape memory actuatorcontroller. The shape memory actuator controller may provide a PWMsignal to the pump, which may be modified based on the battery voltage.This may occur for a fixed ontime, the result being a volume that may bemeasured by volume sensor assembly 148 and fed back into the volumecontroller.

In our preferred embodiment, we vary the duty cycle based on themeasured battery voltage to give you approximately consistent power. Weadjust the duty cycle to compensate for a lower battery voltage. Batteryvoltage may change for two reasons: 1) as batteries are discharged, thevoltage slowly decreases; and 2) when you apply a load to a battery ithas an internal impedence so its voltage dips. This is something thathappens in any type of system, and we compensate for that by adjustingthe duty cycle, thus mitigating the lower or varying battery voltage.Battery voltage may be measured by the microprocessor. In othersystems: 1) voltage may be regulated (put a regulator to maintain thevoltage at a steady voltage); 2) feedback based on something else (i.e.,speed or position of a motor, not necessarily measuring the batteryvoltage).

Other configurations may be utilized to control the shape memoryactuator. For example: A) the shape memory actuator may be controlled atfixed duty cycle with unregulated voltage. As voltage varies, therepeatablity of heating the shape memory actuator is reduced. B) a fixedduty cycle, regulated voltage may be utilized which compensate forchanges in battery voltage. However, regulate the voltage down is lessefficient due to energy of energy. C) the duty cycle may be varied basedon changes in current (which may required more complicated measurementcircuitry. D) The duty cycle may be varied based on measured voltage. E)The duty cycle may be varied based upon the square of the current. orthe square of the voltage divided by resistance. F) the voltage may beapplied for a variable amount of time based on the measured impedance(e.g., may measure impedance using Wheatstone gauge (not shown)). Theimpedance of the shape memory actuator may be correlated to strain(i.e., may correlate how much the SMA moves based on its impedance).

Referring also to FIG. 115 and as discussed above, to enhance the safetyof infusion pump assembly 100, electrical control assembly 110 mayinclude two separate and distinct microprocessors, namely supervisorprocessor 1800 and command processor 1802. Specifically, commandprocessor 1802 may perform the functions discussed above (e.g.,generating SMA drive signal 1612) and may control relay/switchassemblies 1804, 1806 that control the functionality of (in thisexample) shape memory actuators 112, 632 (respectively). Commandprocessor 1802 may receive feedback from signal conditioner 1808concerning the condition (e.g., voltage level) of the voltage signalapplied to shape memory actuators 112, 632. Command processor 1800 maycontrol relay/switch assembly 1810 independently of relay/switchassemblies 1804, 1806. Accordingly, when an infusion event is desired,both of supervisor processor 1800 and command processor 1802 must agreethat the infusion event is proper and must both actuate their respectiverelays/switches. In the event that either of supervisor processor 1800and command processor 1802 fails to actuate their respectiverelays/switches, the infusion event will not occur. Accordingly throughthe use of supervisor processor 1800 and command processor 1802 and thecooperation and concurrence that must occur, the safety of infusion pumpassembly 100 is enhanced.\

The supervisor processor may prevent the command processor fromdelivering when it is not supposed and also may alarm if the commandprocessor does not deliver when it should be delivering. The supervisorprocessor may deactivate the relay/switch assembly if the commandprocessor actuates the wrong switch, or if the command processor ittries to apply power for too long.

The supervisor processor may redundantly doing calculations for how muchinsulin should be delivered (i.e., double checking the calculations ofthe command processor). Command processor may decide the deliveryschedule, and the supervisor processor may redundantly check thosecalculations.

Supervisor also redundantly holds the profiles (delivery profiles) inRAM, so the command processor may be doing the correct calculations, butif is has bad RAM, would cause the command to come up with the wrongresult. The Supervisor uses its local copy of the basal profile, etc.,to double check.

Supervisor can double check AVS measurements, looks at the AVScalculations and applies safety checks. Every time AVS measurement istaken, it double checks.

Referring also to FIG. 116, one or more of supervisor processor 1800 andcommand processor 1802 may perform diagnostics on various portions ofinfusion pump assembly 100. For example, voltage dividers 1812, 1814 maybe configured to monitor the voltages (V1 & V2 respectively) sensed atdistal ends of e.g., shape memory actuator 112. The value of voltages V1& V2 in combination with the knowledge of the signals applied torelay/switch assemblies 1804, 1810 may allow for diagnostics to beperformed on various components of the circuit shown in FIG. 116 (in amanner similar to that shown in illustrative diagnostic table 1816).

As discussed above and as illustrated in FIGS. 115-116, to enhance thesafety of infusion pump assembly 100, electrical control assembly 110may include a plurality of microprocessors (e.g., supervisor processor1800 and command processor 1802), each of which may be required tointeract and concur in order to effectuate the delivery of a dose of theinfusible fluid. In the event that the microprocessors fail tointeract/concur, the delivery of the dose of infusible fluid may failand one or more alarms may be triggered, thus enhancing the safety andreliability of infusion pump assembly 100.

A master alarm may be utilized that tracks the volume error over time.Accordingly, if the sum of the errors becomes too large, the masteralarm may be initiated, indicating that something may be wrong with thesystem. Accordingly, the master alarm may be indicative of a totalvolume comparison being performed and a discrepancy being noticed. Atypical value of the discrepancy required to initiate the master alarmmay be 1.00 milliliters. The master alarm may monitor the sum in a leakyfashion (i.e., Inaccuracies have a time horizon).

Referring also to FIGS. 117A-117B, there is shown one such illustrativeexample of such interaction amongst multiple microprocessors during thedelivery of a dose of the infusible fluid. Specifically, commandprocessor 1802 may first determine 1900 the initial volume of infusiblefluid within volume sensor chamber 620. Command processor 1802 may thenprovide 1902 a “pump power request” message to supervisor processor1800. Upon receiving 1904 the “pump power request” message, supervisorprocessor 1800 may e.g., energize 1906 relay/switch 1810 (thusenergizing shape memory actuator 112) and may send 1908 a “pump poweron” message to command processor 1802. Upon receiving 1910 the “pumppower on” message, command processor 1802 may actuate 1912 e.g., pumpassembly 106 (by energizing relay/switch 1804), during which timesupervisor processor 1800 may monitor 1914 the actuation of e.g., pumpassembly 106.

Once actuation of pump assembly 106 is complete, command processor 1802may provide 1914 a “pump power off” message to supervisor processor1800. Upon receiving 1916 the “pump power off” message, supervisorprocessor 1800 may deenergize 1918 relay/switch 1810 and provide 1920 a“pump power off” message to command processor 1802. Upon receiving 1922the “pump power off” message, command processor 1802 may measure 1924the quantity of infusible fluid pumped by pump assembly 106. This may beaccomplished by measuring the current quantity of fluid within volumesensor chamber 620 and comparing it with the quantity determined above(in step 1900). Once determined 1924, command processor 1802 may provide1926 a “valve open power request” message to supervisor processor 1800.Upon receiving 1928 the “valve open power request” message, supervisorprocessor 1800 may energize 1930 relay/switch 1810 (thus energizingshape memory actuator 632) and may send 1932 a “valve open power on”message to command processor 1802. Upon receiving 1934 the “valve openpower on” message, command processor 1802 may actuate 1936 e.g.,measurement valve assembly 610 (by energizing relay/switch 1806), duringwhich time supervisor processor 1800 may monitor 1938 the actuation ofe.g., measurement valve assembly 610.

Once actuation of measurement valve assembly 610 is complete, commandprocessor 1802 may provide 1940 a “valve power off” message tosupervisor processor 1800. Upon receiving 1942 the “valve power off”message, supervisor processor 1800 may deenergize 1944 relay/switch 1810and provide 1946 a “valve power off” message to command processor 1802.

Upon receiving 1948 the “valve power off” message, command processor1802 may provide 1950 a “valve close power request” message tosupervisor processor 1800. Upon receiving 1952 the “valve close powerrequest” message, supervisor processor 1800 may energize 1954relay/switch 1810 (thus energizing shape memory actuator 652) and maysend 1956 a “power on” message to command processor 1802. Upon receiving1958 the “power on” message, command processor 1802 may actuate 1960 anenergizing relay/switch (not shown) that is configured to energize shapememory actuator 652, during which time supervisor processor 1800 maymonitor 1962 the actuation of e.g., shape memory actuator 652.

As discussed above (and referring temporarily to FIGS. 26A, 26B, 27A,27B & 28), shape memory actuator 652 may be anchored on a first endusing electrical contact 654. The other end of shape memory actuator 652may be connected to bracket assembly 656. When shape memory actuator 652is activated, shape memory actuator 652 may pull bracket assembly 656forward and release valve assembly 634. As such, measurement valveassembly 610 may be activated via shape memory actuator 632. Oncemeasurement valve assembly 610 has been activated, bracket assembly 656may automatically latch valve assembly 610 in the activated position.Actuating shape memory actuator 652 may pull bracket assembly 656forward and release valve assembly 634. Assuming shape memory actuator632 is no longer activated, measurement valve assembly 610 may move to ade-activated state once bracket assembly 656 has released valve assembly634. Accordingly, by actuating shape memory actuator 652, measurementvalve assembly 610 may be deactivated.

Once actuation of shape memory actuator 652 is complete, commandprocessor 1802 may provide 1964 a “power off” message to supervisorprocessor 1800. Upon receiving 1966 the “power off” message, supervisorprocessor 1800 may deenergize 1968 relay/switch 1810 and may provide1970 a “power off” message to command processor 1802. Upon receiving1972 the “power off” message, command processor 1802 may determine thequantity of infusible fluid within volume sensor chamber 620, thusallowing command processor 1802 to compare this measured quantity to thequantity determined above (in step 1924) to determine 1974 the quantityof infusible fluid delivered to the user.

In the event that the quantity of infusible fluid delivered 1974 to theuser is less than the quantity of infusible fluid specified for thebasal/bolus infusion event, the above-described procedure may berepeated (via loop 1976).

Referring also to FIG. 118, there is shown another illustrative exampleof the interaction amongst processors 1800, 1802, this time during thescheduling of a dose of infusible fluid. Command processor 1802 maymonitor 2000, 2002 for the receipt of a basal scheduling message or abolus request message (respectively). Upon receipt 2000, 2002 of eitherof these messages, command processor 1802 may set 2004 the desireddelivery volume and may provide 2006 a “delivery request” message tosupervisor processor 1800. Upon receiving 2008 the “delivery request”message, supervisor processor 1800 may verify 2010 the volume defined2004 by command processor 1802. Once verified 2010, supervisor processor1800 may provide 2012 a “delivery accepted” message to command processor1802. Upon receipt 2014 of the “delivery accepted” message, commandprocessor 1802 may update 2016 the controller (e.g., the controllerdiscussed above and illustrated in FIG. 110) and execute 2018 deliveryof the basal/bolus dose of infusible fluid. Command processor 1808 maymonitor and update 2022 the total quantity of infusible fluid deliveredto the user (as discussed above and illustrated in FIGS. 117A-117B).Once the appropriate quantity of infusible fluid is delivered to theuser, command processor 1802 may provide 2024 a “delivery done” messageto supervisor processor 1800. Upon receipt 2026 of the “delivery done”message, supervisor processor 1800 may update 2028 the total quantity ofinfusible fluid delivered to the user. In the event that the totalquantity of infusible fluid delivered 2018 to the user is less than thequantity defined above (in step 2004), the infusion process discussedabove may be repeated (via loop 2030).

Referring also to FIG. 119, there is shown an example of the manner inwhich supervisor processor 1800 and command processor 1802 may interactwhile effectuating a volume measurements via volume sensor assembly 148(as described above).

Specifically, command processor 1802 may initialize 2050 volume sensorassembly 148 and begin collecting 2052 data from volume sensor assembly148, the process of which may be repeated for each frequency utilized inthe above-described sine sweep. Each time that data is collected for aparticular sweep frequency, a data point message may be provided 2054from command processor 1802, which may be received 2056 by supervisorprocessor 1800.

Once data collection 2052 is completed for the entire sine sweep,command processor 1802 may estimate 2058 the volume of infusible fluiddelivered by infusion pump assembly 100. Command processor 1802 mayprovide 2060 a volume estimate message to supervisor processor 1800.Upon receiving 2062 this volume estimate message, supervisor processor1800 may check (i.e., confirm) 2064 the volume estimate message. Oncechecked (i.e., confirmed), supervisor processor 1800 may provide 2066 averification message to command processor 1802. Once received 2068 fromsupervisor processor 1800, command processor 1802 may set themeasurement status for the dose of infusible fluid delivered by volumesensor assembly 148.

As discussed above and referring temporarily to FIG. 11), the variousembodiments of the infusion pump assembly (e.g., infusion pump assembly100, 100′, 400, 500) discussed above may be configured via a remotecontrol assembly 300. When configurable via remote control assembly 300,the infusion pump assembly may include telemetry circuitry (not shown)that allows for communication (e.g., wired or wireless) between theinfusion pump assembly and e.g., remote control assembly 300, thusallowing remote control assembly 300 to remotely control the infusionpump assembly. Remote control assembly 300 (which may also includetelemetry circuitry (not shown) and may be capable of communicating withthe infusion pump assembly) may include display assembly 302 and inputassembly 304. Input assembly 304 may include slider assembly 306 andswitch assemblies 308, 310. In other embodiments, the input assembly mayinclude a jog wheel, a plurality of switch assemblies, or the like.Remote control assembly 300 may allow the user to program basal andbolus delivery events.

Remote control assembly 300 may include two processors, one processor(e.g., which may include, but is not limited to a CC2510microcontroller/RF transceiver, available from Chipcon AS, of Oslo,Norway) may be dedicated to radio communication, e.g., for communicatingwith infusion pump assembly 100, 100′, 400, 500. The second processorincluded within remote control assembly (which may include but are notlimited to an ARM920T and an ARM922T manufactured by ARM Holdings PLC ofthe United Kingdom) may be a command processor and may perform dataprocessing tasks associated with e.g., configuring infusion pumpassembly 100, 100′, 400, 500.

Further and as discussed above, one embodiment of electrical controlassembly 816 may include three microprocessors. One processor (e.g.,which may include, but is not limited to a CC2510 microcontroller/RFtransceiver, available from Chipcon AS, of Oslo, Norway) may bededicated to radio communication, e.g., for communicating with a remotecontrol assembly 300. Two additional microprocessors (e.g., supervisorprocessor 1800 and command processor 1802) may effectuate the deliveryof the infusible fluid (as discussed above). Examples of supervisorprocessor 1800 and command processor 1802 may include, but is notlimited to an MSP430 microcontroller, available from Texas InstrumentsInc. of Dallas, Tex.

The OS may be a non-preemptive scheduling system, in that all tasks mayrun to completion before the next task is allowed to run regardless ofpriority. Additionally, context switches may not be performed. When atask completes executing, the highest priority task that is currentlyscheduled to run may then be executed. If no tasks are scheduled toexecute, the OS may place the processor (e.g., supervisor processor 1800and/or command processor 1802) into a low power sleep mode and may wakewhen the next task is scheduled. The OS may only be used to manage mainloop code and may leave interrupt-based functionality unaffected.

The OS may be written to take advantage of the C++ language. Inheritanceas well as virtual functions may be key elements of the design, allowingfor easy creation, scheduling and managing of tasks.

At the base of the OS infrastructure may be the ability to keep track ofsystem time and controlling the ability to place the processor in LowPower Mode (LPM; also known as sleep mode). This functionality alongwith the control and configuration of all system clocks may beencapsulated by the SysClocks class.

The SysClocks class may contain the functionality to place the processor(e.g., supervisor processor 1800 and/or command processor 1802) into LPMto reduce energy consumption. While in LPM, the slow real time clock maycontinue to run while the fast system clock that runs the CPU core andmost peripherals may be disabled.

Placing the processor into LPM may always be done by the providedSysClocks function. This function may contain all required power downand power up sequences resulting in consistency whenever entering orexiting LPM. Waking from LPM may be initiated by any interrupts based onthe slow clock.

The OS may keep track of three aspects of time: seconds, millisecondsand the time of day. Concerning seconds, SysClocks may count secondsstarting when the processor comes out of reset. The second counter maybe based on the slow system clocks and, therefore, may incrementregardless of whether the processor is in LPM or at full power. As aresult, it is the boundary at which the processor may wake from sleep toexecute previously scheduled tasks. If a task is scheduled to runimmediately from an interrupt service routine (ISR), the ISR may wakethe processor from LPM on exit and the task may be executed immediately.Concerning milliseconds, in addition to counting the seconds since poweron, SysClocks may also count milliseconds while the processor is in fullpower mode. Since the fast clock is stopped during LPM, the millisecondcounter may not increment. Accordingly, whenever a task is scheduled toexecute based on milliseconds, the processor may not enter LPM.Concerning time of day, the time of day may be represented withinSysClocks as seconds since a particular point time (e.g., seconds since1 Jan. 2004).

The SysClocks class may provide useful functionality to be usedthroughout the Command and Supervisor project code base. The code delaysmay be necessary to allow hardware to settle or actions to be completed.SysClocks may provide two forms of delays, a delay based on seconds or adelay based on milliseconds. When a delay is used, the processor maysimply wait until the desired time has passed before continue with itscurrent code path. Only ISRs may be executed during this time. SysClocksmay provide all of the required functionality to set or retrieve thecurrent time of day.

The word “task” may be associated with more complex scheduling systems;therefore within the OS, task may be represented by and referred to asManaged Functions. The ManagedFunc class may be an abstract base classthat provides all the necessary control members and functionality tomanage and schedule the desired functionality.

The ManagedFunc base class may have five control members, two schedulingmanipulation member functions, and one pure virtual execute functionthat may contain the managed functionality. All of the ManagedFunccontrol members may be hidden from the derived class and may only bedirectly set by the derived class during creation, thus simplifying theuse and enhancing the safety of infusion pump assembly 100, 100′, 400,500.

The Function ID may be set at the time of creation and may never bechanged. All Function IDs may be defined within a single .h file, andthe base ManagedFunc constructor may strongly enforce that the same IDmay not be used for more than one managed function. The ID may alsodefine the priority of a function (with respect to other functions)based upon the function ID assigned, wherein higher priority functionsare assigned lower function IDs. The highest priority task that iscurrently scheduled to execute may execute before lower priority tasks.

All other control members may be used to represent the function'scurrent scheduled state, when it should be executed, and if (uponexecution) the function should be rescheduled to execute in a previouslyset amount of time. Manipulation of these controls and states may beallowed but only through the public member functions (thus enforcingsafety controls on all settings).

To control the scheduling of a managed function, the set start and setrepeat functions may be used. Each of these member functions may be asimple interface allowing the ability to configure or disable repeatsettings as well as control whether a managed function is inactive,scheduled by seconds, milliseconds, or time of day.

Through inheritance, creating a Managed Function may be done by creatinga derived class and defining the pure virtual ‘execute’ functioncontaining the code that needs to be under scheduling control. TheManagedFunc base class constructor may be based upon the unique ID of afunction, but may also be used to set default control values to be usedat start up.

For example to create a function that runs thirty seconds after start upand every 15 seconds thereafter, the desired code is placed into thevirtual execute function and the function ID, scheduled by second state,thirty second start time, and repeat setting of fifteen seconds isprovided to the constructor.

The following is an illustrative code example concerning the creation ofa managed function. In this particular example, a “heartbeat” functionis created that is scheduled to execute for the first time one secondafter startup of infusion pump assembly 100, 100′, 400, 500 and executeevery ten seconds thereafter:

#include “ManagedFunc.h” // The SendGoodFunc is a “heartbeat” statusmessage class SendGoodFunc : public ManagedFunc { public:  // Initializethe managed func to run 2 seconds  after start up  // and repeat everysecond.  SendGoodFunc( ) :   ManagedFunc(IPC_SEND_GOOD,   SCHEDULED_SEC,  1,   true, 10) { };  ~SendGoodFunc( ) { };  protected:   voidexecute(void); }; void SendGoodFunc::execute(void) {  // << code to sendthe heartbeat >> } SendGoodFunc g_sendGoodFunc; // to manipulate theheartbeat timing simply call: //  g_sendGoodFunc.setFuncStart(...)           or g_sendGoodFunc.setRepeat( ... )

The actual execution of the Managed Functions may be controlled andperformed by the SleepManager class. The SleepManager may contain theactual prioritized list of managed functions. This prioritized list offunctions may automatically be populated by the managed functioncreation process and may ensure that each function is created properlyand has a unique ID.

The main role of the SleepManager class may be to have its ‘manage’function called repeatedly from the processors main loop and/or from aendless while loop. Upon each call of manage, the SleepManager mayexecute all functions that are scheduled to run until the SleepManagerhas exhausted all scheduled functions; at which time the SleepManagermay place the processor in LPM. Once the processor wakes from LPM, themanage function may be reentered until the processor is again ready toenter LPM (this process may be repeated until stopped, e.g., by a useror by the system).

If the processor has to be kept in full power mode for an extendedperiod of time (e.g., while an analog-to-digital conversion is beingsampled), the SleepManager may provide functionality to disable enteringLPM. While LPM is disabled, the manage function may continuously searchfor a scheduled task.

The SleepManager may also provide an interface to manipulate thescheduling and repeat settings of any managed function through the useof the unique ID of the function, which may allow any section of code toperform any required scheduling without having direct access to orunnecessary knowledge of the desired ManagedFunc object.

Radio circuitry included within each of infusion pump assembly 100,100′, 400, 500 and remote control assembly 300 may effectuate wirelesscommunication between remote control assembly 300 and infusion pumpassembly 100, 100′, 400, 500. A 2.4 GHz radio communications chip (e.g.,a Texas Instruments CC2510 radio transceiver) with an internal 8051microcontroller may be used for radio communications.

The radio link may balance the following three objectives: linkavailability; latency; and energy.

Concerning link availability, remote control assembly 300 may providethe primary means for controlling the infusion pump assembly 100, 100′,400, 500 and may provide detailed feedback to the user via the graphicaluser interface (GUI) of remote control assembly 300. Concerning latency,the communications system may be designed to provide for low latency todeliver data from remote control assembly 300 to the infusion pumpassembly 100, 100′, 400, 500 (and vice versa). Concerning energy, bothremote control assembly 300 and infusion pump assembly 100, 100′, 400,500 may have a maximum energy expenditure for radio communications.

The radio link may support half-duplex communications. Remote controlassembly 300 may be the master of the radio link, initiating allcommunications. Infusion pump assembly 100, 100′, 400, 500 may onlyrespond to communications and may never initiate communications. The useof such a radio communication system may provide various benefits, suchas: increased security: a simplified design (e.g., for airplane use);and coordinated control of the radio link.

Referring also to FIG. 120A, there is shown one illustrative example ofthe various software layers of the radio communication system discussedabove.

The radio processors included within remote control assembly 300 andinfusion pump assembly 100, 100′, 400, 500 may transfer messagingpackets between an SPI port and a 2.4 GHz radio link (and vice versa).The radio may always be the SPI slave. On infusion pump assembly 100,100′, 400, 500, radio processor (PRP) 1818 (See FIGS. 115-116) mayservice two additional nodes over the SPI port that are upstream (namelycommand processor 1800 and supervisor processor 1802. In someembodiments, on remote control assembly 300, the radio processor (CRP)may service at least one additional node over the SPI port that may beeither upstream or down stream, for example, in some embodiments, theabove-described remote control processor (UI) and the Continuous GlucoseEngine (CGE).

A messaging system may allow for communication of messages betweenvarious nodes in the network. The UI processor of remote controlassembly 300 and e.g., supervisor processor 1800 may use the messagingsystem to configure and initiate some of the mode switching on the twosystem radios. It may be also used by the radios to convey radio andlink status information to other nodes in the network.

When the radio of remote control assembly 300 wishes to gather channelstatistics from the infusion pump assembly 100, 100′, 400, 500 or updatethe master channel list of the radio of infusion pump assembly 100,100′, 400, 500, the radio of remote control assembly 300 may use systemmessages. Synchronization for putting the new updated list into effectmay use flags in the heartbeat messages to remove timing uncertainty.

The radio communication system may be written in C++ to be compatiblewith the messaging software. A four byte radio serial number may be usedto address each radio node. A hash table may be used to provide aone-to-one translation between the device “readable” serial numberstring and the radio serial number. The hash table may provide a morerandomized 8-bit logical address so that pumps (e.g., infusion pumpassembly 100, 100′, 400, 500) or controllers with similar readableserial numbers are more likely to have unique logical addresses. Radioserial numbers may not have to be unique between pumps (e.g., infusionpump assembly 100, 100′, 400, 500) and controllers due to the uniqueroles each has in the radio protocol.

The radio serial number of remote control assembly 300 and the radioserial number of infusion pump assembly 100, 100′, 400, 500 may beincluded in all radio packets except for the RF Pairing Request messagethat may only include the radio serial number of remote control assembly300, thus ensuring that only occur with the remote controlassembly/infusion pump assembly to which it is paired. The CC2510 maysupport a one byte logical node address and it may be advantageous touse one byte of the radio serial number as the logical node address toprovide a level of filtering for incoming packets.

The Quiet_Radio signal may be used by the UI processor of remote controlassembly 300 to prevent noise interference on the board of remotecontrol assembly 300 by other systems on the board. When Quiet_Radio isasserted, the radio application of remote control assembly 300 may senda message to the radio of infusion pump assembly 100, 100′, 400, 500asserting Radio Quiet Mode for a pre-determined period of time. TheQuiet_Radio feature may not be required based on noise interferencelevels measured on the PC board of remote control assembly 300. Duringthis period of time, the radio of remote control assembly 300 may stayin Sleep Mode 2 for up to a maximum of 100 ms. The radio of remotecontrol assembly 300 may come out of Sleep Mode 2 when the Quiet_Radiosignal is de-asserted or the maximum time period has expired. The UIprocessor of remote control assembly 300 may assert Quiet_Radio at leastone radio communication's interval before the event needs to beasserted. The radio of remote control assembly 300 may inform the radioof infusion pump assembly 100, 100′, 400, 500 that communications willbe shutdown during this quiet period. The periodic radio link protocolmay have status bits/bytes that accommodate the Quiet_Radio featureunless Quiet_Radio is not required.

The radio software may integrate with the messaging system and radiobootloader on the same processor, and may be verified using a throughputtest. The radio software may integrate with the messaging system, SPIDriver using DMA, and radio bootloader, all on the same processor (e.g.,the TI CC2510).

The radio of remote control assembly 300 may be configured to consume nomore than 32 mAh in three days (assuming one hundred minutes of fastheartbeat mode communications per day). The radio of infusion pumpassembly 100, 100′, 400, 500 may be configured to consume no more than25 mAh in three days (assuming one hundred minutes of fast heartbeatmode communications per day).

The maximum time to reacquire communications may be ≦6.1 secondsincluding connection request mode and acquisition mode. The radio ofremote control assembly 300 may use the fast heartbeat mode or slowheartbeat mode setting to its advantage in order to conserve power andminimize latency to the user. The difference between the infusion pumpassembly 100, 100′, 400, 500 and remote control assembly 300 enteringacquisition mode may be that the infusion pump assembly 100, 100′, 400,500 needs to enter acquisition mode often enough to ensurecommunications may be restored within the maximum latency period.However, the remote control assembly 300 may change how often to enteracquisition mode with the infusion pump assembly 100, 100′, 400, 500when in slow heartbeat mode and heartbeats are lost. The radio of remotecontrol assembly 300 may have knowledge of the user GUI interaction, butthe infusion pump assembly 100, 100′, 400, 500 may not.

The radio of remote control assembly 300 may set the heartbeat periodfor both radios. The period may be selectable in order to optimize powerand link latency depending on activity. The desired heartbeat period maybe communicated in each heartbeat from the radio of remote controlassembly 300 to the radio of infusion pump assembly 100, 100′, 400, 500.This may not exclusively establish the heartbeat rate of infusion pumpassembly 100, 100′, 400, 500 due to other conditions that determine whatmode to be in. When in fast heartbeat mode, the radio of remote controlassembly 300 may set the heartbeat period to 20 ms if data packets areavailable to send or receive, thus providing low link latencycommunications when data is actively being exchanged.

When in fast heartbeat mode, the radio of remote control assembly 300may set the heartbeat period to 60 ms four heartbeats after a datapacket was last exchanged in either direction on the radio. Keeping theradio heartbeat period short after a data packet has been sent orreceived may assure that any data response packet may be also servicedusing a low link latency. When in slow heartbeat mode, the heartbeatrate may be 2.00 seconds or 6.00 second, depending upon online oroffline status respectively.

The infusion pump assembly 100, 100′, 400, 500 may use the heartbeatrate set by the radio of remote control assembly 300. The radio ofremote control assembly 300 may support the following mode requests viathe messaging system:

-   -   Pairing Mode    -   Connection Mode    -   Acquisition Mode (includes the desired paired infusion pump        assembly 100, 100′, 400, 500 radio serial number)    -   Sync Mode—Fast Heartbeat    -   Sync Mode—Slow Heartbeat    -   RF Off Mode

The radio of infusion pump assembly 100, 100′, 400, 500 may support thefollowing mode requests via the messaging system:

-   -   Pairing Mode    -   Acquisition Mode    -   RF Off Mode

The radio may use a system message to obtain the local radio serialnumber. On remote control assembly 300, the radio may get the serialnumber from the UI processor of remote control assembly 300. The radiomay use a system message to store the paired radio serial number.

Remote control assembly 300 and the radio of infusion pump assembly 100,100′, 400, 500 may issue a status message using the messaging system tothe UI processor of remote control assembly 300 and command processor1802 whenever the following status changes:

-   -   Online Fast: Successful connection    -   Online Fast: Change from Acquisition Mode to Fast Heartbeat Mode    -   Online Slow: Successful request change from Fast Heartbeat to        Slow Heartbeat    -   Offline: Automatic change to Search Sync mode due to lack of        heartbeat exchanges.

Online Fast: Successful request change from Slow Heartbeat to FastHeartbeat

-   -   Offline: Bandwidth falls below 10% in Sync Mode    -   Online: Bandwidth rises above 10% in Search Sync mode    -   Offline: Successful request change to RF Off Mode

The radio configuration message may be used to configure the number ofradio retries. This message may be sent over the messaging system. TheUI processor of remote control assembly 300 will send this command toboth the radio of remote control assembly 300 and the radio of infusionpump assembly 100, 100′, 400, 500 to configure these radio settings.

There may be two parameters in the radio configuration message: namelythe number of RF retries (e.g., the value may be from 0 to 10); and theradio offline parameters (e.g., the value may be from 1 to 100 inpercent of bandwidth).

The radio application on both the remote control assembly 300 andinfusion pump assembly 100, 100′, 400, 500 may have an API that allowsthe messaging system to configure the number of RF retries and radiooffline parameters.

The following parameters may be recommended for the radio hardwareconfiguration:

-   -   Base Radio Specifications    -   MSK    -   250 kbps over air baud rate    -   Up to 84 channels    -   Channel spacing 1000 kHz    -   Filter bandwidth 812 kHz    -   No Manchester encoding    -   Data whitening    -   4 byte preamble    -   4 byte sync (word)    -   CRC appended to packet    -   LQI (Link Quality Indicator) appended to packet    -   Automatic CRC filtering enabled

Forward Error Correction (FEC) may or may not be utilized. AlthoughForward Error Correction (FEC) may be used to increase the effectivesignal dynamic range by approximately 3 dB, FEC requires fixed packetsizes and doubles the number of over the air bits for the same fixedsize message.

The radio may function within 1.83 meters distance under nominaloperating conditions (except in pairing mode). It may be a goal that theradio function within 7.32 meters distance under nominal operatingconditions. The transmit power level may be 0 dBm (except in pairingmode) and the transmit power level in pairing mode may be −22 dBm. Sincethe desired radio node address of infusion pump assembly 100, 100′, 400,500 may be not known by the remote control assembly 300 in pairing mode,both infusion pump assembly 100, 100′, 400, 500 and remote controlassembly 300 may use a lower transmit power to reduce the likelihood ofinadvertently pairing with another infusion pump assembly.

AES Encryption may be used for all packets but may not be required, asthe Texas Instruments CC2510 radio transceiver includes thisfunctionality. If AES encryption is used, fixed keys may be utilized, asfixed keys provide a quick way to enable encryption without passingkeys. However, key exchange may be provided for in future versions ofinfusion pump assembly 100, 100′, 400, 500. The fixed keys may becontained in one separate header source file with no other variables butthe fixed keys data, thus allowing for easier management of read accessof the file.

The radio software may support the following eight modes:

-   -   Pairing Mode    -   RF Off Mode    -   Connection Mode    -   Acquisition Mode    -   Fast Heartbeat Mode    -   Slow Heartbeat Mode    -   Search Sync Mode    -   Sync'ed Acquisition Mode which are graphically depicted in FIGS.        120B-120C.

Pairing may be the process of exchanging radio serial numbers betweenremote control assembly 300 and infusion pump assembly 100, 100′, 400,500. Remote control assembly 300 may be “paired” with infusion pumpassembly 100, 100′, 400, 500 when infusion pump assembly 100, 100′, 400,500 knows its serial number. Infusion pump assembly 100, 100′, 400, 500may be “paired” with remote control assembly 300 when remote controlassembly 300 knows its serial number.

Pairing mode (which is graphically depicted in FIG. 120D) may requirethat four messages to be exchanged over the RF link:

-   -   RF Pairing Request (broadcast from Remote control assembly 300        to any Infusion pump assembly 100, 100′, 400, 500)    -   RF Pairing Acknowledge (from Infusion pump assembly 100, 100′,        400, 500 to Remote control assembly 300)    -   RF Pairing Confirm Request (from Remote control assembly 300 to        Infusion pump assembly 100, 100′, 400, 500)    -   RF Pairing Confirm Acknowledge (from Infusion pump assembly 100,        100′, 400, 500 to Remote control assembly 300)

Additionally, remote control assembly 300 may cancel the pairing processat any time via the RF pairing abort message (from remote controlassembly 300 to infusion pump assembly 100, 100′, 400, 500. Pairing modemay not support messaging system data transfers.

The radio of infusion pump assembly 100, 100′, 400, 500 may enterpairing mode upon receiving a pairing mode request message. It may bethe responsibility of supervisor processor 1800 on infusion pumpassembly 100, 100′, 400, 500 to request the radio to enter pairing modeif there is no disposable attached to infusion pump assembly 100, 100′,400, 500 and the user has pressed the button of infusion pump assembly100, 100′, 400, 500 for six seconds. The radio of infusion pump assembly100, 100′, 400, 500 may set the appropriate transmit power level forpairing mode. Infusion pump assembly 100, 100′, 400, 500 may only bepaired with one remote control assembly 300 at a time.

Upon receiving the first valid RF pairing request message while inpairing mode, the radio of infusion pump assembly 100, 100′, 400, 500may use the serial number of remote control assembly 300 for theduration of pairing mode and respond with an RF pairing acknowledgemessage containing the radio serial number infusion pump assembly 100,100′, 400, 500.

The radio of infusion pump assembly 100, 100′, 400, 500 may timeout ofpairing mode automatically after 2.0±0.2 seconds if no RF pairingrequest is received. The radio of infusion pump assembly 100, 100′, 400,500 may issue a pairing request received message after transmitting theRF pairing acknowledge. This message to supervisor processors will allowfeedback to the user during the pairing confirm process. The radio ofinfusion pump assembly 100, 100′, 400, 500 may automatically timeout ofpairing mode in 1.0±0.1 minutes after sending an RF pairing acknowledgeunless an RF pairing confirm request is received. The radio of infusionpump assembly 100, 100′, 400, 500 may issue a store paired radio serialnumber message if an RF pairing confirm request message is receivedafter receiving a RF pairing request message. This action may store theradio serial number of remote control assembly 300 in the non-volatilememory of infusion pump assembly 100, 100′, 400, 500 and may overwritethe existing pairing data for the infusion pump assembly 100, 100′, 400,500.

The radio of infusion pump assembly 100, 100′, 400, 500 may transmit anRF pairing confirm acknowledge and exit pairing mode after theacknowledgment from the store paired radio serial number message isreceived. This may be the normal exit of pairing mode on infusion pumpassembly 100, 100′, 400, 500 and may result in infusion pump assembly100, 100′, 400, 500 powering down until connection mode or paring modeentered by the user.

If the radio of infusion pump assembly 100, 100′, 400, 500 exits pairingmode upon successfully receiving a pairing confirm request message, thenthe radio of infusion pump assembly 100, 100′, 400, 500 may revert tothe newly paired remote control assembly 300 and may send a pairingcompletion success message to command processor 1802. The radio ofinfusion pump assembly 100, 100′, 400, 500 may exit pairing mode uponreceiving an RF pairing abort message. The radio of infusion pumpassembly 100, 100′, 400, 500 may exit pairing mode upon receiving apairing abort request message addressed to it. This may allow commandprocessor 1802 or supervisor processor 1800 to abort the pairing processlocally on the infusion pump assembly 100, 100′, 400, 500.

The radio of remote control assembly 300 may enter pairing mode uponreceiving a pairing mode request message. It may be the responsibilityof the UI processor of remote control assembly 300 to request that theradio enter pairing mode under the appropriate conditions. The radio ofremote control assembly 300 may set the appropriate transmit power levelfor pairing mode. The radio of remote control assembly 300 may transmitRF pairing requests until an RF pairing acknowledge is received orpairing is aborted.

The radio of remote control assembly 300 may automatically abort pairingmode if the RF pairing acknowledge message is not received within30.0±1.0 seconds after entering pairing mode. Upon receiving the firstvalid RF pairing acknowledge message while in pairing mode, the radio ofremote control assembly 300 may send a pairing success message to the UIprocessor of remote control assembly 300 that includes the serial numberof infusion pump assembly 100, 100′, 400, 500 and may use that serialnumber for the duration of pairing mode. This message may provide ameans for the UI processor of remote control assembly 300 to have theuser confirm the serial number of the desired infusion pump assembly100, 100′, 400, 500. If the radio of remote control assembly 300receives multiple responses (concerning a single pairing request) frominfusion pump assembly 100, 100′, 400, 500, the first valid one may beused.

The Radio of remote control assembly 300 may only accept an RF pairingconfirm acknowledge messages after an RF pairing acknowledge is receivedwhile in pairing mode. The radio of remote control assembly 300 maytransmit the RF pairing confirm message upon receiving a pair confirmrequest message from the UI processor of remote control assembly 300.

The radio of remote control assembly 300 may check that infusion pumpassembly 100, 100′, 400, 500 confirms the pairing before adding infusionpump assembly 100, 100′, 400, 500 to the pairing list. The radio ofremote control assembly 300 may issue a store paired radio serial numbermessage if an RF pairing complete message is received. This action mayallow the UI processor of remote control assembly 300 to store the newserial number of infusion pump assembly 100, 100′, 400, 500 and provideuser feedback of a successful pairing. It may be the responsibility ofthe UI processor of remote control assembly 300 to manage the list ofpaired infusion pump assemblies.

The radio of remote control assembly 300 may send an RF pairing abortmessage and exit pairing mode upon receiving a pairing abort requestmessage. This may allow the UI processor of the remote control assembly300 to abort the pairing process on both the remote control assembly 300and acknowledged infusion pump assembly 100, 100′, 400, 500.

In connection request mode, the radio of remote control assembly 300 mayattempt to acquire each infusion pump assembly 100, 100′, 400, 500 inits paired infusion pump assembly list and retrieve its “connectionready” status. The “connection” process (which is graphically depictedin FIG. 120E) may allow remote control assembly 300 to quickly identifyone of its paired infusion pump assemblies that may be ready to be used.The radio of remote control assembly 300 may be capable of performingthe connection request mode with up to six paired infusion pumpassemblies. Connection request mode may be only supported on remotecontrol assembly 300 and may be a special form of acquisition mode. Inconnection request mode, remote control assembly 300 may connect withthe first infusion pump assembly to respond. However, each message maybe directed to a specific infusion pump assembly serial number.

The radio of remote control assembly 300 may obtain the latest pairedinfusion pump assembly serial number list upon entering connection mode.The radio of remote control assembly 300 may enter connection mode uponreceiving a connection mode request message. It may be theresponsibility of the UI processor of remote control assembly 300 torequest that the radio enter connection mode when it desirescommunications with a paired infusion pump assembly. The radio of remotecontrol assembly 300 may issue a connection assessment message to the UIprocessor of remote control assembly 300 containing the radio serialnumber of the first infusion pump assembly, if any, that is “connectionready”. The radio of remote control assembly 300 may generate theconnection assessment message within thirty seconds of enteringconnection request mode. The radio of remote control assembly 300 mayexit connection request mode upon receipt of the connection assessmentacknowledgement and transition to fast heartbeat mode. The radio ofremote control assembly 300 may exit connection request mode uponreceipt of a connection request abort message from the UI processor ofremote control assembly 300.

On remote control assembly 300, acquisition mode may be used to find aparticular paired infusion pump assembly. The radio of remote controlassembly 300 may send RF RUT (aRe yoU There) packets to the desiredpaired infusion pump assembly. If the infusion pump assembly receivesthe RF RUT message, it may respond to the radio of remote controlassembly 300. Multiple channels may be used in the acquisition modealgorithm to improve the opportunity for the radio of remote controlassembly 300 to find the paired infusion pump assembly.

The radio of remote control assembly 300 may enter acquisition mode uponreceiving an acquisition mode request or fast heartbeat mode requestmessage while in RF Off Mode. The radio of remote control assembly 300may enter sync'ed acquisition mode upon receiving an acquisition moderequest or fast heartbeat mode request message while in search syncmode. It may be the responsibility of the UI processor of remote controlassembly 300 to request that the radio enter acquisition mode when theRF link is off-line and remote control assembly 300 desirescommunications with infusion pump assembly 100, 100′, 400, 500.

The radio of remote control assembly 300 may only communicate with onepaired infusion pump assembly 100, 100′, 400, 500 (except in pairing andconnection modes). When communications are lost, the UI processor ofremote control assembly 300 may use acquisition mode (at some periodicrate limited by the power budget) to attempt to restore communications.

Infusion pump assembly 100, 100′, 400, 500 may enter acquisition modeunder the following conditions:

-   -   When in Radio Off Mode and Acquisition Mode may be requested    -   When Search Sync Mode times out due to lack of heartbeats

Upon entering acquisition mode, the radio of infusion pump assembly 100,100′, 400, 500 may obtain the serial number of the last stored pairedremote control assembly 300. The radio of infusion pump assembly 100,100′, 400, 500 may only communicate with the remote control assembly towhich it has been “paired” (except while in the “pairing request” mode).The radio of infusion pump assembly 100, 100′, 400, 500 may transitionfrom acquisition mode to fast heartbeat mode upon successfully acquiringsynchronization with the remote control assembly 300. The acquisitionmode of infusion pump assembly 100, 100′, 400, 500 may be capable ofacquiring synchronization within 6.1 seconds, which may implies that theinfusion pump assembly 100, 100′, 400, 500 may always be listening atleast every ˜6 seconds when in acquisition mode.

Data packets may be sent between two paired devices when the two devicesare in sync mode and online. The two devices may sync via a heartbeatpacket before data packets are exchanged. Each radio may send datapackets at known time intervals after the heartbeat exchange. Theinfusion pump assembly 100, 100′, 400, 500 may adjust its timing toanticipate reception of a packet. The radio may support one data packetin each direction on each heartbeat. The radio may provide a negativeresponse to a fast heartbeat mode request if the radio if offline. Theradio of remote control assembly 300 may change to fast heartbeat modeif a system request for fast heartbeat mode is received while in slowheartbeat mode and the radio is online.

Upon transitioning to fast heartbeat mode from acquisition mode, theradio of remote control assembly 300 may send the master channel listmessage. The master channel list may be built by the radio of remotecontrol assembly 300 and sent to the radio of infusion pump assembly100, 100′, 400, 500 to allow a selection of frequency hopping channelsbased on historical performance. When in fast heartbeat mode or slowheartbeat mode, periodic heartbeat messages may be exchanged between theradio of remote control assembly 300 and the radio of infusion pumpassembly 100, 100′, 400, 500. The periodicity of these messages may beat the heartbeat rate. The heartbeat messages may allow data packettransfers to take place and may also exchange status information. Thetwo radios may exchange the following status information: Quiet Mode,data availability, buffer availability, heartbeat rate, and priorchannel performance. It may be a goal to keep the packet size of theheartbeat messages small in order to conserve power. The radio mayprovide for a maximum data packet size of eighty-two bytes when in SyncMode. The messaging system may be designed to support packet payloadsizes up to sixty-four bytes. This maximum size was selected as anoptimal trade-off between minimum messages types and non-fragmentedmessages. The eighty-two bytes may be the maximum packet size of themessaging system including packet overhead.

The messaging system has an API that may allow the radio protocol tosend an incoming radio packet to it. The messaging system may also havean API that allows the radio protocol to get a packet for transmissionover the radio network. The messaging system may be responsible forpacket routing between the radio protocol and the SPI port. Data packetsmay be given to the messaging system for processing. The messagingsystem may have an API that allows the radio protocol to obtain a countof the number of data packets waiting to be sent over the radio network.The radio protocol may query the messaging system on each heartbeat todetermine if data packets are available to send over the radio network.It may be desirable for the software to check the availability of amessage just before the heartbeat is sent to minimize round trip messagelatency.

The radio protocol may be capable of buffering one incoming radio datapacket and passing the packet to the messaging system. The radioprotocol may send the data packet to the messaging system upon receiptof the data packet. The message system may be responsible for routingradio data packets to the proper destination node. The radio protocolmay be capable of buffering one packet from the messaging system.

The radio protocol may be responsible for acknowledging receipt of validdata packets over the RF link via an RF ACK reply packet to the sendingradio. The RF ACK packet may contain the source and destination radioserial numbers, RF ACK command identification, and sequence number ofthe data packet being acknowledged.

The radio transmitting a radio data packet may retransmit that radiodata packet on the next heartbeat with the same sequence number if an RFACK is not received and the retry count is within the maximum RF retriesallowed. It may be expected that, from time to time, interference willcorrupt a transmission on a particular frequency. An RF retry allows thesame packet to be retransmitted at the next opportunity at a differentfrequency. The sequence number provides a means of uniquely identifyingthe packet over a short time window. The number of radio packet retriesmay be configurable using the radio configuration command. Allowing moreretries may increase the probability of a packet being exchanged butintroduces more latency for a round trip messages. The default number ofradio retries at power up may be ten (i.e., the maximum transmissionattempts before dropping the message).

A one byte (modulo 256) radio sequence number may be included in allradio data packets over the RF link. Since the radio may be responsiblefor retrying data packet transmission if not acknowledged, the sequencenumber may provide a way for the two radios to know if a data packet isa duplicate. The transmitted sequence number may be incremented for eachnew radio data packet and may be allowed to rollover. When a data packetis successfully received with the same sequence number as the previoussuccessfully received data packet (and in the same direction), the datapacket may be ACK'd and the received data packet discarded. This mayremove duplicate packets generated by the RF protocol before they areintroduced into the network. Note that it may be possible that multipledata packets in a row may need to be dropped with the same sequencenumber under extreme situations.

If a heartbeat is missed, the radio of remote control assembly 300 andthe radio of infusion pump assembly 100, 100′, 400, 500 may attempt tosend and listen respectively for subsequent heartbeats. The radio ofremote control assembly 300 and the radio of infusion pump assembly 100,100′, 400, 500 may automatically change from fast heartbeat mode or slowheartbeat mode to search sync mode if heartbeats are missed for twoseconds. This may minimize power consumption when the link is lost byallowing the radios to continue to use their synchronizationinformation, as two seconds allows sufficient time to hop through allchannels.

The radio may be considered online while in the following modes:

-   -   Fast Heartbeat mode    -   Slow Heartbeat mode

as these are the only conditions where messaging system traffic may beexchanged. All other conditions may be considered offline.

The radio may initialize to radio off mode at the start of codeexecution from reset. When code first executes on the radio processor,the initial state may be the radio off mode to allow other processors toperform self-tests before requesting the radio to be active. Thisrequirement does not intend to define the mode when waking from sleepmode. The radio may cease RF communications when set to radio off mode.On remote control assembly 300, this mode may be intended for use on anairplane to suppress RF emissions. Since infusion pump assembly 100,100′, 400, 500 only responds to transmissions from remote controlassembly 300 (which will have ceased transmitting in airplane mode),radio off mode may only be used on infusion pump assembly 100, 100′,400, 500 when charging.

Command processor 1802 may be informed of airplane mode and that,therefore, the RF was intentionally turned off on remote controlassembly 300 so that it does not generate walk-away alerts. However,this may be completely hidden from the radio of infusion pump assembly100, 100′, 400, 500.

The radio of remote control assembly 300 and the radio of infusion pumpassembly 100, 100′, 400, 500 may periodically attempt to exchangeheartbeats in order to reestablish data bandwidth while in search syncmode. The radio of remote control assembly 300 may transition to radiooff mode after twenty minutes of search sync mode with no heartbeatssuccessfully exchanged.

The radio of infusion pump assembly 100, 100′, 400, 500 may transitionto acquisition mode after twenty minutes of search sync mode with noheartbeats successfully exchanged. Listening during pre-agreed timeslots may be the most efficient use of power for infusion pump assembly100, 100′, 400, 500 to re-establish the RF link. After a loss ofcommunications, the crystal tolerance and temperature drift may make itnecessary to expand the receive window of infusion pump assembly 100,100′, 400, 500 over time. Staying in search sync mode for extendedperiods (e.g., 5-20 minutes) after communications loss may cause theinstantaneous power consumed to exceed the average power budgeted forthe radio of infusion pump assembly 100, 100′, 400, 500. The radio ofremote control assembly 300 may not be forced to expand its window, sostaying in search sync mode may be very power efficient. Acquisitionmode may consume more power for remote control assembly 300. Twentyminutes may be used as a compromise to balance power consumption on boththe radio of remote control assembly 300 and the radio of infusion pumpassembly 100, 100′, 400, 500.

The radio of remote control assembly 300 and the radio of infusion pumpassembly 100, 100′, 400, 500 may transition to slow heartbeat mode ifthey successfully exchange three of the last five heartbeats.Approximately every six seconds, a burst of five heartbeats may beattempted. If three of these are successful, the bandwidth may beassumed to be sufficient to transition to slow heartbeat mode. The radioof infusion pump assembly 100, 100′, 400, 500 may be acquirable while insearch sync mode with a latency of 6.1 seconds. This may imply that theinfusion pump assembly 100, 100′, 400, 500 may always be listening atleast every ˜6 seconds when in search sync mode.

Radio protocol performance statistics may be necessary to promotetroubleshooting of the radio and to assess radio performance. Thefollowing radio performance statistics may be maintained by the radioprotocol in a data structure:

NAME SIZE DESCRIPTION TX Heartbeat Count 32 Bits Total transmittedheartbeats RX Heartbeat Count 32 bits Total valid received heartbeatsCRC Errors 16 bits Total packets received over the RF link which weredropped due to bad CRC. This may be a subset of RX Packets Nacked. FirstRetry Count 32 bits Total number of packets which were successfullyacknowledged after 1 retry Second Retry Count 32 bits Total number ofpackets which were successfully acknowledged after 2 retries Third RetryCount 32 bits Total number of packets which were successfullyacknowledged after 3 retries Fourth Retry Count 32 bits Total number ofpackets which were successfully acknowledged after 4 retries Fifth RetryCount 16 bits Total number of packets which were successfullyacknowledged after 5 retries Sixth Retry Count 16 bits Total number ofpackets which were successfully acknowledged after 6 retries SeventhRetry Count 16 bits Total number of packets which were successfullyacknowledged after 7 retries Eighth Retry Count 16 bits Total number ofpackets which were successfully acknowledged after 8 retries Ninth RetryCount 16 bits Total number of packets which were successfullyacknowledged after 9 retries Tenth Retry Count 16 bits Total number ofpackets which were successfully acknowledged after 10 retries DroppedRetry Count 16 bits Total number of packets which were dropped aftermaximum retries attempts Duplicate Packet Count 16 bits Total number ofreceived packets dropped due to duplicate packet 1 to 5 Missed Fast ModeHops 16 bits Count of 1 to 5 consecutive missed hops in Fast mode (i.e.not received) 6 to 16 Missed Fast Mode Hops 16 bits Count of 6 to 16consecutive missed hops in Fast mode. 17 to 33 Missed Fast Mode Hops 16bits Count of 17 to 33 consecutive missed hops in Fast mode 34+ MissedFast Mode Hops 16 bits Count of 34 or more consecutive missed hops inFast mode 1 to 2 Missed Slow Mode Hops 16 bits Count of 1 to 2consecutive missed hops in Slow mode (i.e. not received) 3 to 5 MissedSlow Mode Hops 16 bits Count of 3 to 5 consecutive missed hops in Slowmode 5 to 7 Missed Slow Mode Hops 16 bits Count of 5 to 7 consecutivemissed hops in Slow mode 8+ Missed Slow Mode Hops 16 bits Count of 8 ormore consecutive missed hops in Slow mode Destination Radio SerialNumber 16 bits Count of received packets in which the destination madeit Mismatch past the hardware filtering but does not match this radio'sserial number. This may be not an error but indicates that the radio maybe waking up and receiving (but not processing) packets intended forother radios Total Walkaway Time (minutes) 16 bits Total Walkaway Events16 bits Together with total walkaway time provides an average walkawaytime Number of Pairing Attempts 16 bits Total Time in Acquisition Mode16 bits (Infusion pump assembly 100, 100′, 400, 500 Only) TotalAcquisition Mode Attempts 16 bits Successful Acquisition Count 16 bitsCount of transistions (Remote control assembly 300 Only) from Connect orAcquisition Mode to Fast Heartbeat Mode Requested Slow Heartbeat Mode 16bits Transitions Automatic Slow Heartbeat Mode 16 bits Transitions Radiooffline messages sent 16 bits Radio online messages sent 16 bits

A #define DEBUG option (compiler option) may be used to gather thefollowing additional radio performance statistics per each channel (16bit numbers):

-   -   Number of missed hops    -   CCA good count    -   CCA bad count    -   Average RSSI (accumulated for good RX packets only)    -   Dropped from Frequency Hop List count    -   Acquisition Mode count (found pair on this channel)

The debug option may be used to gather engineering only statistics. Ifprocessor performance, power, and memory allow, it may be desirable tokeep this information at runtime. The radio statistics may be madeavailable to the messaging system.

Link quality may be intended to be used on remote control assembly 300to provide a bar indicator, similar to a cell phone, of the radio linkquality. Link quality may be made available to both remote controlassembly 300 and infusion pump assembly 100, 100′, 400, 500. It may beanticipated that the link quality status will consist of a one byteindicator of the

quality of the radio link.

The radio may change frequency for each heartbeat. An adaptive pseudorandom frequency hopping algorithm may be used for sync mode andheartbeat attempts in search sync mode. It may be a goal to usesixty-four channels for frequency hopping. An algorithm may be developedto adaptively generate a channel list on remote control assembly 300 forfrequency hopping. The radio of remote control assembly 300 may build,maintain, and distribute the master channel list. Prior channelstatistics and historical performance information may be obtained fromthe radio of infusion pump assembly 100, 100′, 400, 500 by the radio ofremote control assembly 300 using the messaging system as needed to meetperformance requirements. By building the channel list from theperspective of both units, the radio interference environment of bothunits may be considered. The radios may adaptively select hoppingchannels to meet the round trip message latency, while operating in adesirable RF environment.

Occlusions and/or leaks may occur anywhere along the fluid delivery pathof infusion pump assembly 100. For example and referring to FIG. 121,occlusions/leaks may occur: in the fluid path between reservoir 118 andreservoir valve assembly 614; in the fluid path between reservoir valveassembly 614 and pump assembly 106; in the fluid path between pumpassembly 106 and volume sensor valve assembly 612; in the fluid pathbetween volume sensor valve assembly 612 and volume sensor chamber 620;in the fluid path between volume sensor chamber 620 and measurementvalve assembly 610; and in the fluid path between measurement valveassembly 610 and the tip of disposable cannula 138. Infusion pumpassembly 100 may be configured to execute one or more occlusion/leakdetection algorithms that detect and locate such occlusions/leaks andenhance the safety/reliability of infusion pump assembly 100.

As discussed above, when administering the infusible fluid, infusionpump assembly 100 may first determine the volume of infusible fluidwithin volume sensor chamber 620 prior to the administration of the doseof infusible fluid and may subsequently determine the volume ofinfusible fluid within volume sensor chamber 620 after theadministration of the dose of infusible fluid. By monitoring thesevalues, the occurrence of occlusions/leaks may be detected.

Occlusion Type—Total:

When a total occlusion is occurring, the difference between the initialmeasurement prior to the administration of the dose of infusible fluidand the final measurement after the administration of the dose ofinfusible fluid will be zero (or essentially zero), indicating a largeresidual quantity of infusible fluid within volume sensor chamber 620.Accordingly, no fluid may be leaving volume sensor chamber 620.

Specifically, if the tip of disposable cannula is occluded, the fluidpath down stream of volume sensor chamber 620 will fill with fluid andeventually become pressurized to a level equivalent to the mechanicalpressure exerted by spring diaphragm 628. Accordingly, upon measurementvalve assembly 610 opening, zero (or essentially zero) fluid will bedispensed and, therefore, the value of the initial and finalmeasurements (as made by volume sensor assembly 148) will essentially beequal.

Upon detecting the occurrence of such a condition, a total occlusionflag may be set and infusion pump assembly 100 may e.g., trigger analarm, thus indicating that the user needs to seek alternative means forreceiving their therapy.

Occlusion Type—Partial:

When a partial occlusion is occurring, the difference between theinitial measurement prior to the administration of the dose of infusiblefluid and the final measurement after the administration of the dose ofinfusible fluid will indicate that less than a complete dose ofinfusible fluid was delivered. For example, assume that at the end of aparticular pumping cycle, volume sensor assembly 148 indicated that 0.10microliters of infusible fluid were present in volume sensor chamber620. Further, assume that measurement value assembly 610 is subsequentlyclosed and pump assembly 106 is subsequently actuated, resulting involume sensor chamber 620 being filed with the infusible fluid. Furtherassume that volume sensor assembly 148 determines that volume sensorchamber 620 is now filled with 1.00 microliters of infusible fluid(indicating a pumped volume of 0.90 microliters).

Accordingly, upon the opening of measurement valve assembly 610, thequantity of infusible fluid included within volume sensor chamber wouldbe expected to drop to 0.10 microliters (or reasonably close thereto).However, in the event of a partial occlusion, due to aslower-than-normal flow rate from volume sensor chamber 620, thequantity of infusible fluid within volume sensor chamber 620 may only bereduced to 0.40 microliters (indicating a delivered volume of 0.60microliters). Accordingly, by monitoring the difference between thepumped volume (0.90 microliters) and the delivered volume (0.60microliters), the residual volume may be defined and the occurrence of apartial occlusion may be detected.

Upon detecting the occurrence of such a condition, a partial occlusionflag may be set and infusion pump assembly 100 may e.g., trigger analarm, thus indicating that the user needs to seek alternative means forreceiving their therapy. However, as this is indicative of a partialocclusion (as opposed to a complete occlusion), the issuance of an alarmmay be delayed, as the partial occlusion may clear itself.

Alternatively, infusion pump assembly 100 may: calculate a pump ontimeto volume delivered ratio; track it through time; and track by using afast moving and a slow moving exponential average of the pump ontime.The exponential average may be tracked, in a fashion similar to theleaky sum integrator. The infusion pump assembly 100 may filter signaland look for a fast change. The rate of fluid outflow and/or residualvolume may be monitored. If the residual volume does not change, thenthere may be a total occlusion. If the residual volume changed, they maybe a partial occlusion. Alternatively still, the residual values may besummed. If the number of valve actuations or the latch time is beingvaried, the fluid flow rate may be examined, even if you build uppressure in volume sensor assembly 148.

Total/Partial Empty Reservoir:

When reservoir 118 is becoming empty, it will become more difficult tofill volume sensor chamber 620 to the desired level. Typically, pumpassembly 106 is capable of pumping 1.0 microliters per millisecond. Forexample, assume that an “empty” condition for volume sensor chamber 620is 0.10 microliters and a “full” condition for volume sensor chamber 620is 1.00 microliters. However, as reservoir 118 begins to empty, it maybecome harder for pump assembly 106 to fill volume sensor chamber 620 tothe “full” condition and may consistently miss the goal. Accordingly,during normal operations, it may take one second for pump assembly 106to fill volume sensor chamber 620 to the “full” condition and, asreservoir 118 empties, it may take three seconds to fill volume sensorchamber 620 to the “full” condition. Eventually, if reservoir 118completely empties, volume sensor chamber 620 may never be able toachieve a “full condition”. Accordingly, the inability of pump assembly106 to fill volume sensor chamber 620 to a “full” condition may beindicative of reservoir 118 being empty. Alternatively, the occurrenceof such a condition may be indicative of other situations (e.g., thefailure of pump assembly 106 or an occlusion in the fluid path prior tovolume sensor chamber 620). Infusion pump assembly 100 may determine thedifference between the “full” condition and the amount actually pumped.These differences may be summed and the made up for once the reservoircondition is addressed.

Upon detecting the occurrence of such a condition, an empty flag may beset and infusion pump assembly 100 may e.g., trigger an alarm, thusindicating that the user needs to e.g., replace disposable housingassembly 114.

Additionally, as reservoir 118 empties, reservoir 118 will eventuallyresult in a “vacuum” condition and the ability of pump assembly 106 todeliver fluid to volume sensor chamber 620 may be compromised. Asdiscussed above, volume controller 1602 may include feed forwardcontroller 1652 for setting an initial “guess” concerning “on-time”signal 1606, wherein this initial guess is based upon a pump calibrationcurve. For example, in order for pump assembly 106 to deliver 0.010units of infusible fluid, feed forward controller 1652 may define aninitial “on-time” of e.g., one millisecond. However, as reservoir 118begins to empty, due to compromised pumping conditions, it may take twomilliseconds to deliver 0.010 units of infusible fluid. Further, asreservoir 118 approaches a fully empty condition, it make take tenmilliseconds to deliver 0.010 units of infusible fluid. Accordingly, theoccurrence of reservoir 118 approaching an empty condition may bedetected by monitoring the level at which the actual operation of pumpassembly 106 (e.g., two milliseconds to deliver 0.010 units of infusiblefluid) differs from the anticipated operation of pump assembly 106(e.g., one millisecond to deliver 0.010 units of infusible fluid).

Upon detecting the occurrence of such a condition, a reserve flag may beset and infusion pump assembly 100 may e.g., trigger an alarm, thusindicating that the user will need to e.g., replace disposable housingassembly 114 shortly.

Leak Detection:

In the event of a leak (e.g., a leaky valve or a rupture/perforation)within the fluid path, the ability of the fluid path to retain fluidpressure may be compromised. Accordingly, in order to check for leakswithin the fluid path, a bleed down test may be performed in which pumpassembly 106 is used to pressurize volume sensor chamber 620. Volumesensor assembly 148 may then perform a first volume measurement (asdescribed above) to determine the volume of infusible fluid withinvolume sensor chamber 620. Infusion pump assembly 100 may then wait adefined period of time to allow for bleed down in the event of a leak.For example, after a sixty second bleed down period, volume sensorassembly 148 may perform a second volume measurement (as describedabove) to determine the volume of infusible fluid within volume sensorchamber 620. If there are no leaks, the two volume measurements shouldbe essentially the same. However, in the event of a leak, the secondmeasurement may be less then the first measurement. Additionally,depending on the severity of the leak, pump assembly 106 may beincapable of filling volume sensor chamber 620. Typically, a leak checkmay be performed as part of a delivery of infusible fluid.

In the event that the difference between the first volume measurementand the second volume measurement exceeds an acceptable threshold, aleak flag may be set and infusion pump assembly 100 may e.g., trigger analarm, thus indicating that the user needs to seek alternative means forreceiving their therapy

As discussed above, infusion pump assembly 100 may include supervisorprocessor 1800, command processor 1802, and radio processor 1818.Unfortunately, once assembled, access to electrical control assembly 110within infusion pump assembly 100 very limited. Accordingly, the onlymeans to access electrical control assembly 110 (e.g., for upgradingflash memories) may be through the communication channel establishedbetween infusion pump assembly 100, 100′, 400, 500 and remote controlassembly 300, or via electrical contacts 834 used by battery charger1200.

Electrical contacts 834 may be directly coupled to radio processor 1818and may be configured to provide I2C communication capability forerasing/programming any flash memory (not shown) included within radioprocessor 1818. The process of loading a program into radio processor1818 may provide a means for erasing/programming of the flash memoriesin both the supervisor processor 1800 and command processor 1802.

When programming supervisor processor 1800 or command processor 1802,the program (i.e., data) to be loaded into flash memory accessible bysupervisor processor 1800 or command processor 1802 may be provided in aplurality of data blocks. This is because the radio processor 1818 maynot have enough memory to hold the entire flash image of the software asone block.

Referring also to FIG. 122, there is shown one illustrative example ofthe manner in which the various systems within infusion pump assembly100, 100′, 400, 500 may be interconnected. For example, battery charger1200 may be coupled to computing device 2100 (e.g., a personal computer)via bus translator 2102, which converts e.g., RS232 formatted data toe.g., I2C formatted data. Bus translator 2102 may execute a pass-throughprogram that effectuates the above-described translation. Batterycharger 1200 may be coupled to radio processor 181 via electricalcontacts 834 (described above). Radio processor 1818 may then be coupledto supervisor processor 1800 and command processor 1802 via e.g., anRS232 bus. Radio processor 1818 may execute an update program thatallows radio processor 1818 to control/orchestrate the updating of theflash memories accessible by supervisor processor 1800 and commandprocessor 1802. Accordingly, through the use of the above-describedcoupling, software updates obtained by computing device 2100 may beuploaded to flash memory (not shown) accessible by supervisor processor1800 and command processor 1802. The above-described software updatesmay be command line program that may be automatically invoked by ascript process.

As discussed above, infusion pump assembly 100, 100′ 400, 500 may beconfigured to deliver an infusible fluid to a user. Further and asdiscussed above, infusion pump assembly 100, 100′ 400, 500 may deliverthe infusible fluid via sequential, multi-part, infusion events (thatmay include a plurality of discrete infusion events) and/or one-timeinfusion events. However, in some embodiments, infusion pump assembly100, 100′ 400, 500 may deliver stacking bolus infusion events. Forexample, a user may request the delivery of a bolus, e.g., 6 units.While the 6 units are in the process of being delivered to the user, theuser may request a second bolus, e.g., 3 units. In some embodiments ofinfusion pump assembly 100, 100′ 400, 500 may deliver the second bolusat the completion of the first bolus.

Examples of other such sequential, multi-part, infusion events mayinclude but are not limited to a basal infusion event and anextended-bolus infusion event. As is known in the art, a basal infusionevent refers to the repeated injection of small (e.g. 0.05 unit)quantities of infusible fluid at a predefined interval (e.g. every threeminutes) that may be repeated until stopped, e.g., by a user or by thesystem. Further, the basal infusion rates may be pre-programmed and mayinclude specified rates for pre-programmed time-frames, e.g., a rate of0.50 units per hour from 6:00 am-3:00 pm; a rate of 0.40 units per hourfrom 3:00 pm-10:00 pm; and a rate of 0.35 units per hour from 10:00pm-6:00 am. However, the basal rate may be 0.025 units per hour, and maynot change according to pre-programmed time-frames. The basal rates maybe repeated regularly/daily until otherwise changed.

Further and as is known in the art, an extended-bolus infusion event mayrefer to the repeated injection of small (e.g. 0.05 unit) quantities ofinfusible fluid at a predefined interval (e.g. every three minutes) thatis repeated for a defined number of intervals (e.g., three intervals) orfor a defined period of time (e.g., nine minutes). An extended-bolusinfusion event may occur simultaneously with a basal infusion event.

If multiple infusion events conflict with each other, infusion pumpassembly 100, 100′ 400, 500 may prioritize the infusion event in thefollow manner.

Referring also to FIG. 123, assume for illustrative purposes only thatthe user configures infusion pump assembly 100, 100′ 400, 500 toadminister a basal dose (e.g. 0.05 units) of infusible fluid every threeminutes. The user may utilize remote control assembly 300 to define abasal infusion event for the infusible fluid (e.g., 1.00 units perhour).

Infusion pump assembly 100, 100′ 400, 500 may then determine an infusionschedule based upon the basal infusion event defined. Once determined,infusion pump assembly 100, 100′ 400, 500 may administer the sequential,multi-part, infusion event (e.g., 0.05 units of infusible fluid everythree minutes). Accordingly, while administering the sequential,multi-part, infusion event, infusion pump assembly 100, 100′ 400, 500:may infuse a first 0.05 unit dose 2200 of the infusible fluid at t=0:00(i.e., a first discrete infusion event), may infuse a second 0.05 unitdose 2202 of the infusible fluid at t=3:00 (i.e., a second discreteinfusion event); may infuse a third 0.05 unit dose 2204 of the infusiblefluid at t=6:00 (i.e., a third discrete infusion event); may infuse afourth 0.05 unit dose 2206 of the infusible fluid at t=9:00 (i.e., afourth discrete infusion event); and may infuse a fifth 0.05 unit dose2208 of the infusible fluid at t=12:00 (i.e., a fifth discrete infusionevent). As discussed above, this pattern of infusing 0.05 unit doses ofthe infusible fluid every three minutes may be repeated until stopped,e.g., by a user or by the system, in this example, as this is anillustrative example of a basal infusion event.

Further, assume for illustrative purposes that the infusible fluid isinsulin and sometime after the first 0.05 unit dose 2200 of infusiblefluid is administered (but before the second 0.05 unit dose 2202 ofinfusible fluid is administered), the user checks their blood glucoselevel and realizes that their blood glucose level is running a littlehigher than normal. Accordingly, the user may define an extended bolusinfusion event via remote control assembly 300. An extended bolusinfusion event may refer to the continuous infusion of a definedquantity of infusible fluid over a finite period of time. However, assuch an infusion methodology is impractical/undesirable for an infusionpump assembly, when administered by such an infusion pump assembly, anextended bolus infusion event may refer to the infusion of additionalsmall doses of infusible fluid over a finite period of time.

Accordingly, the user may utilize remote control assembly 300 to definean extended bolus infusion event for the infusible fluid (e.g., 0.20units over the next six minutes), which may be confirmed in a mannerdiscussed above. While, in this example, the extended bolus infusionevent is described as 0.20 units over the next six minutes, this is forillustrative purposes only and is not intended to be a limitation ofthis disclosure, as either or both of the unit quantity and total timeinterval may be adjusted upward or downward. Once defined and/orconfirmed, infusion pump assembly 100, 100′ 400, 500 may determine aninfusion schedule based upon the extended bolus infusion event defined;and may administer the infusible fluid. For example, infusion pumpassembly 100, 100′ 400, 500 may deliver 0.10 units of infusible fluidevery three minutes for the next two interval cycles (or six minutes),resulting in the delivery of the extended bolus dose of infusible fluiddefined by the user (i.e., 0.20 units over the next six minutes).

Accordingly, while administering the second, sequential, multi-part,infusion event, infusion pump assembly 100, 100′ 400, 500 may infuse afirst 0.10 unit dose 2210 of the infusible fluid at t=3:00 (e.g., afteradministering the second 0.05 unit dose 2202 of infusible fluid).Infusion pump assembly 100, 100′ 400, 500 may also infuse a second 0.10unit dose 2212 of the infusible fluid at t=6:00 (e.g., afteradministering the third 0.05 unit dose 2204 of infusible fluid).

Assume for illustrative purposes only that after the user programsinfusion pump assembly 100, 100′ 400, 500 via remote control assembly300 to administer the first sequential, multi-part, infusion event(i.e., 0.05 units infused every three minute interval repeatedcontinuously) and administer the second sequential, multi-part, infusionevent (i.e., 0.10 units infused every three minute interval for twointervals), the user decides to eat a very large meal. Predicting thattheir blood glucose level might increase considerably, the user mayprogram infusion pump assembly 100, 100′ 400, 500 (via remote controlassembly 300) to administer a one-time infusion event. An example ofsuch a one-time infusion event may include but is not limited to anormal bolus infusion event. As is known in the art, a normal bolusinfusion event refers to a one-time infusion of the infusible fluid.

For illustrative purposes only, assume that the user wishes to haveinfusion pump assembly 100, 100′ 400, 500 administer a bolus dose ofthirty-six units of the infusible fluid. Infusion pump assembly 100,100′ 400, 500 may monitor the various infusion events being administeredto determine whether a one-time infusion event is available to beadministered. If a one-time infusion event is available foradministration, infusion pump assembly 100, 100′ 400, 500 may delay theadministration of at least a portion of the sequential, multi-part,infusion event.

Continuing with the above-stated example, once the user completes theprogramming of infusion pump assembly 100, 100′ 400, 500 to deliverone-time infusion event 2214 (i.e., the thirty-six unit bolus dose ofthe infusible fluid), upon infusion pump assembly 100, 100′ 400, 500determining that the one-time infusion event is available foradministration, infusion pump assembly 100, 100′ 400, 500 may delay theadministration of each sequential, multi-part infusion event andadminister the available one-time infusion event.

Specifically and as discussed above, prior to the user programminginfusion pump assembly 100, 100′ 400, 500 to deliver one-time infusionevent 2214, infusion pump assembly 100, 100′ 400, 500 was administeringa first sequential, multi-part, infusion event (i.e., 0.05 units infusedevery three minute interval repeated continuously) and administering asecond sequential, multi-part, infusion event (i.e., 0.10 units infusedevery three minute interval for two intervals).

For illustrative purposes only, the first sequential, multi-part,infusion event may be represented within FIG. 123 as 0.05 unit dose 2200@ t=0:00, 0.05 unit dose 2202 @ t=3:00, 0.05 unit dose 2204 @ t=6:00,0.05 unit dose 2206 @ t=9:00, and 0.05 unit dose 2208 @ t=12:00. As thefirst sequential, multi-part, infusion event as described above is abasal infusion event, infusion pump assembly 100, 100′ 400, 500 maycontinue to infuse 0.05 unit doses of the infusible fluid at threeminute intervals indefinitely (i.e., until the procedure is cancelled bythe user).

Further and for illustrative purposes only, the second sequential,multi-part, infusion event may be represented within FIG. 123 as 0.10unit dose 2210 @ t=3:00 and 0.10 unit dose 2212 @ t=6:00. As the secondsequential, multi-part, infusion event is described above as an extendedbolus infusion event, infusion pump assembly 100, 100′ 400, 500 maycontinue to infuse 0.10 unit doses of the infusible fluid at threeminute intervals for exactly two intervals (i.e., the number ofintervals defined by the user).

Continuing with the above-stated example, upon infusion pump assembly100, 100′ 400, 500 determining that the thirty-six unit normal bolusdose of the infusible fluid (i.e., one-time infusion event 2214) isavailable for administration, infusion pump assembly 100, 100′ 400, 500may delay the administration of each sequential, multi-part infusionevent and may start administering one-time infusion event 2214 that isavailable for administration.

Accordingly and for illustrative purposes only, assume that uponcompletion of the programming of infusion pump assembly 100, 100′ 400,500 to deliver the thirty-six unit normal bolus does of the infusiblefluid (i.e., the one-time infusion event), infusion pump assembly 100,100′ 400, 500 begins administering one-time infusion event 2214. Beingthat one-time infusion event 2214 is comparatively large, it may takelonger than three minutes (i.e., the time interval between individualinfused doses of the sequential, multi-part, infusion events) and one ormore of the individual infused doses of the sequential, multi-part,infusion events may need to be delayed.

Specifically, assume that it will take infusion pump assembly 100, 100′400, 500 greater than six minutes to infuse thirty-six units of theinfusible fluid. Accordingly, infusion pump assembly 100, 100′ 400, 500may delay 0.05 unit dose 2202 (i.e., scheduled to be infused @ t=3:00),0.05 unit dose 2204 (i.e., scheduled to be infused @ t=6:00), and 0.05unit dose 2206 (i.e., scheduled to be infused @ t=9:00) until afterone-time infusion event 2214 (i.e., the thirty-six unit normal bolusdose of the infusible fluid) is completely administered. Further,infusion pump assembly 100, 100′ 400, 500 may delay 0.10 unit dose 2210(i.e., scheduled to be infused @ t=3:00 and 0.10 unit dose 2212 (i.e.,scheduled to be infused @ t=6:00) until after one-time infusion event2214.

Once administration of one-time infusion event 2214 is completed byinfusion pump assembly 100, 100′ 400, 500, any discrete infusion eventsincluded within the sequential, multi-part, infusion event that weredelayed may be administered by infusion pump assembly 100, 100′ 400,500. Accordingly, once one-time infusion event 2214 (i.e., thethirty-six unit normal bolus dose of the infusible fluid) is completelyadministered, infusion pump assembly 100, 100′ 400, 500 may administer0.05 unit dose 2202, 0.05 unit dose 2204, 0.05 unit dose 2206, 0.10 unitdose 2210, and 0.10 unit dose 2212.

While infusion pump assembly 100, 100′ 400, 500 is shown to administer0.05 unit dose 2202, then 0.10 unit dose 2210, then 0.05 unit dose 2204,then 0.10 unit dose 2212, and then 0.05 unit dose 2206, this is forillustrative purposes only and is not intended to be a limitation ofthis disclosure, as other configurations are possible and are consideredto be within the scope of this disclosure. For example, upon infusionpump assembly 100, 100′ 400, 500 completing the administration ofone-time infusion event 2214 (i.e., the thirty-six unit normal bolusdose of the infusible fluid), infusion pump assembly 100, 100′ 400, 500may administer all of the delayed discrete infusion events associatedwith the first sequential, multi-part infusion event (i.e., namely 0.05unit dose 2202, 0.05 unit dose 2204, and 0.05 unit dose 2206). Infusionpump assembly 100, 100′ 400, 500 may then administer all of the delayeddiscrete infusion events associated with the second sequential,multi-part infusion event (i.e., 0.10 unit dose 2210, and 0.10 unit dose2212).

While one-time infusion event 2214 (i.e., the thirty-six unit normalbolus dose of the infusible fluid) is shown as being infused beginningat t=3:00, this is for illustrative purposes only and is not intended tobe a limitation of this disclosure. Specifically, infusion pump assembly100, 100′ 400, 500 may not need to begin infusing one-time infusionevent 2214 at one of the three-minute intervals (e.g., t=0:00, t=3:00,t=6:00, t=9:00, or t=12:00) and may begin administering one-timeinfusion event 2214 at any time.

While each discrete infusion event (e.g., 0.05 unit dose 2202, 0.05 unitdose 2204, 0.05 unit dose 2206, 0.10 unit dose 2210, and 0.10 unit dose2212) and one-time infusion event 2214 are shown as being a singleevent, this is for illustrative purposes only and is not intended to bea limitation of this disclosure. Specifically, at least one of theplurality of discrete infusion events e.g., 0.05 unit dose 2202, 0.05unit dose 2204, 0.05 unit dose 2206, 0.10 unit dose 2210, and 0.10 unitdose 2212) may include a plurality of discrete infusion sub-events.Further, one-time infusion event 2214 may include a plurality ofone-time infusion sub-events.

Referring also to FIG. 124 and for illustrative purposes, 0.05 unit dose2202 is shown to include ten discrete infusion sub-events (e.g.,infusion sub-events 2216 ₁₋₁₀), wherein a 0.005 unit dose of theinfusible fluid is infused during each of the ten discrete infusionsub-events. Additionally, 0.10 unit dose 2210 is shown to include tendiscrete infusion sub-events (e.g., infusion sub-events 2218 ₁₋₁₀),wherein a 0.01 unit dose of the infusible fluid is delivered during eachof the ten discrete infusion sub-events. Further, one-time infusionevent 2214 may include e.g., three-hundred-sixty one-time infusionsub-events (not shown), wherein a 0.1 unit dose of the infusible fluidis delivered during each of the three-hundred-sixty one-time infusionsub-events. The number of sub-events defined above and the quantity ofthe infusible fluid delivered during each sub-event is solely forillustrative purposes only and is not intended to be a limitation ofthis disclosure, as the number of sub-events and/or the quantity of theinfusible fluid delivered during each sub-event may be increased ordecreased depending upon e.g., the design criteria of infusion pumpassembly 100, 100′ 400, 500.

Before, after, or in between the above-described infusion sub-events,infusion pump assembly 100, 100′ 400, 500 may confirm the properoperation of infusion pump assembly 100, 100′ 400, 500 through the useof any of the above-described safety features (e.g., occlusion detectionmethodologies and/or failure detection methodologies).

In the exemplary embodiments, the infusion pump assembly may bewirelessly controlled by a remote control device. In the exemplaryembodiments, a split ring resonator antenna may be used for wirelesscommunication between the infusion pump assembly and the remote controldevice (or other remote device). The term “wirelessly controlled” refersto any device that may receive input, instructions, data, or other,wirelessly. Further, a wirelessly controlled insulin pump refers to anyinsulin pump that may wirelessly transmit and/or receive data fromanother device. Thus, for example, an insulin pump may both receiveinstructions via direct input by a user and may receive instructionswirelessly from a remote controller.

Referring to FIG. 127 and FIG. 131, an exemplary embodiment of a splitring resonator antenna adapted for use in a wirelessly controlledmedical device, and is used in the exemplary embodiment of the infusionpump assembly, includes at least one split ring resonator antenna(hereinafter “SRR antenna”) 2508, a wearable electric circuit, such as awirelessly controlled medical infusion apparatus (hereinafter “infusionapparatus”) 2514, capable of powering the antenna, and a control unit2522.

In various embodiments, a SRR antenna 2508 may reside on the surface ofa non-conducting substrate base 2500, allowing a metallic layer (orlayers) to resonate at a predetermined frequency. The substrate base2500 may be composed of standard printed circuit board material such asFlame Retardant 2 (FR-2), FR-3, FR-4, FR-5, FR-6, G-10, CEM-1, CEM-2,CEM-3, CEM-4, CEM-5, Polyimide, Teflon, ceramics, or flexible Mylar. Themetallic resonating bodies comprising a SRR antenna 2508 may be made oftwo rectangular metallic layers 2502, 2504, made of, for example,platinum, iridium, copper, nickel, stainless steel, silver or otherconducting materials. In other various embodiments, a SRR antenna 2508may contain only one metallic resonating body.

In the exemplary embodiment, a gold-plated copper outer layer 2502,surrounds, without physically contacting, a gold-plated copper innerring 2504. That is, the inner ring 2504 resides in the cavity 2510 (oraperture) formed by the outer layer 2502. The inner ring 2504 maycontain a gap, or split 2506, along its surface completely severing thematerial to form an incomplete ring shape. Both metallic resonatingbodies 2502, 2504 may reside on the same planar surface of the substratebase 2500. In such a configuration, the outer layer 2502 may by drivenvia a transmission line 2512 coupled to the outer layer 2502, forexample. Additionally, in various other embodiments, a transmission line2512 may be coupled to the inner ring 2504.

Antenna design software, such as AWR Microwave Office, capable ofsimulating electromagnetic geometries, such as, antenna performance, maysignificantly decrease the time required to produce satisfactorydimensions compared to physically fabricating and testing antennas.Accordingly, with aid of such software, the SRR antenna 2508 may bedesigned such that the geometric dimensions of the resonant bodies 2502,2504 facilitate an operational frequency of 2.4 GHz. FIG. 132 depictsthe exemplary dimensions of the inner ring 2504 and outer layer 2502,and the positioning of the cavity 2510 in which the inner ring 2504resides. The distance in between the outer layer 2502 and the inner ring2504 is a constant 0.005 inches along the perimeter of the cavity 2510.However, in other embodiments, the distance between the outer layer andthe inner ring may vary and in some embodiments, the operationalfrequency may vary.

In various embodiments, a SRR antenna 2508 may have dimensions such thatit could be categorized as electrically small, that is, the greatestdimension of the antenna being far less than one wavelength atoperational frequency.

In various other embodiments, a SRR antenna 2508 may be composed of oneor more alternatively-shaped metallic outer layers, such as circular,pentagonal, octagonal, or hexagonal, surrounding one or more metallicinner layers of similar shape. Further, in various other embodiments,one or more metallic layers of a SRR antenna 2508 may contain gaps inthe material, forming incomplete shapes.

Referring to FIG. 130, a SRR antenna 2508 having the exemplary geometryexhibits acceptable return loss and frequency values when placed incontact with human skin. As shown in FIG. 130, focusing on the band ofinterest denoted by markers 1 and 2 on the graph, return loss prior tocontact with human skin is near −15 dB while monitoring a frequency bandcentered around 2.44 GHz. Return loss during contact with human skin, asshown in FIG. 130A, remains a suitable value near −25 dB at the samefrequency, yielding approximately 97% transmission power.

These results are favorable especially as compared with a non-split ringresonator antenna type, such as the Inverted-F. Return loss of anInverted-F antenna may exhibit a difference when the antenna contactshuman skin, resulting in a low percentage of power transmitted outwardfrom the antenna. By way of example, as shown in FIG. 133, and againfocusing on the band of interest denoted by markers 1 and 2 on thegraph, return loss of an Inverted-F antenna prior to contact with humanskin is near −25 dB at a frequency centered around 2.44 GHz. Return lossduring contact with human skin is nearly −2 dB at the same frequency,yielding approximately 37% power transmission.

Integration with a Wireless Medical Device

In the exemplary embodiment, referring to FIG. 132 and FIG. 128, oneapplication of a SRR antenna 2508 may be integration into a wearableinfusion apparatus 2514 capable of delivering fluid medication to auser/patient 2524. In such an application, the safety of theuser/patient is dependent on fluid operation between these electricalcomponents, thus reliable wireless transmission to and from a controlunit 2522 is of great importance.

An infusion apparatus 2514 may be worn directly on the human body. Byway of example, such a device may be attached on or above the hip jointin direct contact with human skin, placing the SRR antenna 2508 at riskof unintended dielectric loading causing a frequency shift in electricaloperation. However, in such an application, electrical characteristicsof the SRR antenna 2508 which allow it to be less sensitive to nearbyparasitic objects are beneficial in reducing or eliminating degradationto the performance. A controlling component, such as a control unit 2522(generally shown in FIG. 131), may be paired with an infusion apparatus2514, and may be designed to transmit and receive wireless signals toand from the infusion apparatus 2514 at a predetermined frequency, suchas 2.4 GHz. In the exemplary embodiment, the control unit 2522 serves asthe main user interface through which a patient or third party maymanage insulin delivery. In other embodiments, infusion apparatus 2514may utilize a SRR antenna 2508 to communicate with one or more controlunits 2522.

In various embodiments, a number of different wireless communicationprotocols may be used in conjunction with the SRR antenna 2508, as theprotocol and data types to be transferred are independent of theelectrical characteristics of the antenna. However, in the exemplaryembodiment, a bi-directional master/slave means of communicationorganizes the data transfer through the SRR antenna 2508. The controlunit 2522 may act as the master by periodically polling the infusionapparatus 2514, or slave, for information. In the exemplary embodiment,only when the slave is polled, the slave may send signals to the controlunit 2522 only when the slave is polled. However, in other embodiments,the slave may send signals before being polled. Signals sent by way ofthis system may include, but are not limited to, control, alarm, status,patient treatment profile, treatment logs, channel selection andnegotiation, handshaking, encryption, and check-sum. In someembodiments, transmission through the SRR antenna 2508 may also behalted during certain infusion operations as an added precaution againstelectrical disruption of administration of insulin to the patient.

In the exemplary embodiment, the SRR antenna 2508 may be coupled toelectrical source circuitry via one or more pins 2516 on a transmissionline 2512. In various other embodiments a transmission line may comprisea wire, pairs of wire, or other controlled impedance methods providing achannel by which the SRR antenna 2508 is able to resonate at a certainfrequency. The transmission line 2512 may reside on the surface of thesubstrate base 2500 and may be composed of the same material as the SRRantenna 2508, such as gold-plated copper. Additionally, a ground planemay be attached to the surface of the substrate base opposite thetransmission line 2512.

The electrical circuitry coupled to the SRR antenna 2508 may apply an RFsignal to the end of the transmission line 2512 nearest the circuitry,creating an electromagnetic field throughout, and propagating from, theSRR antenna 2508. The electrical circuitry coupled to the SRR antenna2508 facilitates resonance at a predetermined frequency, such as 2.4GHz. Preferably, transmission line 2512 and SRR antenna 2508 both haveimpedances of 50 Ohms to simplify circuit simulation andcharacterization. However, in other various embodiments, thetransmission line and split ring resonator antenna may have otherimpendence values, or a different resonating frequency.

Referring to FIG. 129, a signal processing component(s) 2518, such as, afilter, amplifier, or switch, may be integrated into the transmissionline 2512, or at some point between the signal source connection pins2516 and the SRR antenna 2508. In the exemplary embodiment, the signalprocessing component 2518 is a band-pass filter to facilitate desiredsignal processing, such as, allowing only the exemplary frequency to betransmitted to the antenna, and rejecting frequencies outside thatrange. In the exemplary embodiment, a Combline band-pass filter 2518 maybe included in the transmission line 2512 between the antenna and thesignal source. However in other embodiments, any other signal processingdevice, for example, but not limited to, filters, amplifiers, or anyother signal processing devices known in the art.

In various embodiments, a SRR antenna 2508 may be composed of metallicbodies capable of resonating on a flexible or rigid substrate. As shownin FIG. 128 and FIG. 3, the exemplary embodiment incorporates a curvedSRR antenna on a flexible Polyimide substrate 2520. Polyimide may be theexemplary material because it tends to be more flexible than alternativesubstrates. This configuration may allow for simplified integration intocircular-shaped devices (such as a wirelessly controlled medicalinfusion apparatus 2514), devices with irregular-shaped externalhousing, or devices in which saving space is paramount.

In various embodiments, both control unit 2522 and base unit 2514 mayincorporate a split SRR antenna 2508. This configuration may provebeneficial where the control unit is meant to be handheld, in closeproximity to human skin, or is likely to be in close proximity to avarying number of materials with varying dielectric constants.

In various other embodiments, a SRR antenna 2508 may be integrated intoa human or animal limb replacement. As prosthetic limbs are becomingmore sophisticated the electrical systems developed to control andsimulate muscle movements require much more wiring and data transferamong subsystems. Wireless data transfer within a prosthetic limb mayreduce weight through reduced physical wiring, conserve space, and allowgreater freedom of movement. However, common antennas in such a systemmay be susceptible to dielectric loading. Similar to the previouslymentioned benefits of integrating a SRR antenna 2508 into a wirelesslycontrolled medical infusion apparatus, a prosthetic limb, such as arobotic arm, may also come into contact with human skin or otherdielectric materials and benefit from the reduction of electricaldisturbances associated with such an antenna. In other variousembodiments, the SRR antenna 2508 may be integrated into any devicecomprised of the electrical components capable of powering andtransmitting/receiving data to an antenna and susceptible to electricaldisturbances associated with proximity to dielectric materials.

In various embodiments, a SRR antenna 2508 may be integrated into aconfiguration of medical components in which one or more implantablemedical devices, operating within the human body, communicate wirelesslyto a handheld, body-mounted, or remote control unit. In certainembodiments, both body-mounted and in-body wireless devices may utilizea SRR antenna 2508 for wireless communication. Additionally, one or moreof the components utilizing a SRR antenna 2508 may be completelysurrounded by human skin, tissue or other dielectric material. By way ofexample, such a configuration may be used in conjunction with a heartmonitoring/control system where stability and consistency of wirelessdata transmission are of fundamental concern.

In various other embodiments, a SRR antenna 2508 may be integrated intothe embodiments of the infusion pump assembly. configuration of medicalcomponents in which one or more electrical sensors positioned on, orattached to, the human body wirelessly communicate to a remotetransceiving unit. By way of example, a plurality of electrodespositioned on the body may be coupled to a wireless unit employing a SRRantenna 2508 for wireless transmission to a remotely locatedelectrocardiogram machine. By way of further example, a wirelesstemperature sensor in contact with human skin may employ SRR antenna2508 for wireless communication to a controller unit for temperatureregulation of the room in which the sensor resides.

A number of embodiments have been described. Nevertheless, it will beunderstood that various modifications may be made. Accordingly, otherembodiments are within the scope of the following claims.

What is claimed is:
 1. A wearable infusion pump assembly comprising: areservoir for receiving an infusible fluid; a fluid delivery systemconfigured to deliver the infusible fluid from the reservoir to anexternal infusion set, wherein the fluid delivery system includes: avolume sensor assembly configured to receive, and measure the volume of,a quantity of the infusible fluid from the reservoir, the volume sensorassembly including: an acoustically contiguous region having a volumethat varies based upon the quantity of infusible fluid received from thereservoir, an acoustic energy emitter configured to provide acousticenergy at a plurality of frequencies to excite a gas included within theacoustically contiguous region for measuring the volume of the quantityof the infusible fluid, a first acoustic energy receptor for receivingat least a portion of the acoustic energy provided by the acousticenergy emitter and defining an acoustic response for each of theplurality of frequencies, and a second acoustic energy receptor forreceiving at least a portion of the acoustic energy provided by theacoustic energy emitter and defining an acoustic reference for each ofthe plurality of frequencies; a disposable housing assembly includingthe reservoir, a first portion of the fluid delivery system, a firstportion of a pump assembly, a first portion of a first valve assembly,and a first portion of a second valve assembly; a reusable housingassembly including a second portion of the fluid delivery system, asecond portion of the pump assembly, a second portion of the first valveassembly, and a second portion of the second valve assembly; at leastone processor; and a computer readable medium coupled to the at leastone processor, the computer readable medium including a plurality ofinstructions stored thereon which, when executed by the at least oneprocessor, cause the at least one processor to perform operationscomprising: determining a phase relationship between the acousticresponse and the reference for each of the plurality of frequencies, andcalculating a change of volume characteristic based, at least in part,upon the phase relationship between the acoustic response and theacoustic reference for each of the plurality of frequencies; wherein thepump assembly is configured to extract the quantity of the infusiblefluid from the reservoir and provide the quantity of the infusible fluidto the volume sensor assembly; wherein the first valve assembly isconfigured to selectively isolate the pump assembly from the reservoir;and wherein the second valve assembly is configured to selectivelyisolate the volume sensor assembly from the external infusion set. 2.The wearable infusion pump assembly of claim 1 wherein the acousticallycontiguous region includes: a variable volume chamber having a volumethat varies based upon the quantity of infusible fluid received from thereservoir, at least one fixed volume chamber having a volume that isconstant regardless of the quantity of infusible fluid received from thereservoir, and at least one acoustic port for acoustically coupling thevariable volume chamber to the at least one fixed volume chamber.
 3. Thewearable infusion pump assembly of claim 2 wherein: the first acousticenergy receptor is an invariable microphone positioned proximate thevariable volume chamber; and the second acoustic energy receptor is areference microphone positioned proximate the at least one fixed volumechamber.
 4. A wearable infusion pump assembly comprising: a reusablehousing assembly; a disposable housing assembly including a reservoirfor receiving an infusible fluid; a releasable engagement assemblyconfigured to allow the reusable housing assembly to releasably engagethe disposable housing assembly; and a filling station including aninfusible fluid supply, the filling station comprising at least onelocking tab, wherein the filling station releasably engages thedisposable portion, and wherein the filling station is configured toreleasably fluidly couple the reservoir and effectuate the delivery ofthe infusible fluid from the filling station to the reservoir.
 5. Thewearable infusion pump assembly of claim 4, wherein the filling stationincludes a plurality of moveable button assemblies that interact withthe disposable portion when the filling station is clipped thereto toadjust a volume of the reservoir.
 6. The wearable infusion pump assemblyof claim 5, wherein the plurality of moveable button assemblies arecantilever members.